follow_pfnmap_start() suffers from two problems:
(1) We are not re-fetching the pmd/pud after taking the PTL
Therefore, we are not properly stabilizing what the lock actually
protects. If there is concurrent zapping, we would indicate to the
caller that we found an entry, however, that entry might already have
been invalidated, or contain a different PFN after taking the lock.
Properly use pmdp_get() / pudp_get() after taking the lock.
(2) pmd_leaf() / pud_leaf() are not well defined on non-present entries
pmd_leaf()/pud_leaf() could wrongly trigger on non-present entries.
There is no real guarantee that pmd_leaf()/pud_leaf() returns something
reasonable on non-present entries. Most architectures indeed either
perform a present check or make it work by smart use of flags.
However, for example loongarch checks the _PAGE_HUGE flag in pmd_leaf(),
and always sets the _PAGE_HUGE flag in __swp_entry_to_pmd(). Whereby
pmd_trans_huge() explicitly checks pmd_present(), pmd_leaf() does not do
that.
Let's check pmd_present()/pud_present() before assuming "the is a present
PMD leaf" when spotting pmd_leaf()/pud_leaf(), like other page table
handling code that traverses user page tables does.
Given that non-present PMD entries are likely rare in VM_IO|VM_PFNMAP, (1)
is likely more relevant than (2). It is questionable how often (1) would
actually trigger, but let's CC stable to be sure.
This was found by code inspection.
Link: https://lkml.kernel.org/r/20260323-follow_pfnmap_fix-v1-1-5b0ec10872b3@kernel.org
Fixes: 6da8e9634b ("mm: new follow_pfnmap API")
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Multiple sysfs command paths dereference contexts_arr[0] without first
verifying that kdamond->contexts->nr == 1. A user can set nr_contexts to
0 via sysfs while DAMON is running, causing NULL pointer dereferences.
In more detail, the issue can be triggered by privileged users like
below.
First, start DAMON and make contexts directory empty
(kdamond->contexts->nr == 0).
# damo start
# cd /sys/kernel/mm/damon/admin/kdamonds/0
# echo 0 > contexts/nr_contexts
Then, each of below commands will cause the NULL pointer dereference.
# echo update_schemes_stats > state
# echo update_schemes_tried_regions > state
# echo update_schemes_tried_bytes > state
# echo update_schemes_effective_quotas > state
# echo update_tuned_intervals > state
Guard all commands (except OFF) at the entry point of
damon_sysfs_handle_cmd().
Link: https://lkml.kernel.org/r/20260321175427.86000-3-sj@kernel.org
Fixes: 0ac32b8aff ("mm/damon/sysfs: support DAMOS stats")
Signed-off-by: Josh Law <objecting@objecting.org>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> [5.18+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
On arm64 server, we found folio that get from migration entry isn't locked
in softleaf_to_folio(). This issue triggers when mTHP splitting and
zap_nonpresent_ptes() races, and the root cause is lack of memory barrier
in softleaf_to_folio(). The race is as follows:
CPU0 CPU1
deferred_split_scan() zap_nonpresent_ptes()
lock folio
split_folio()
unmap_folio()
change ptes to migration entries
__split_folio_to_order() softleaf_to_folio()
set flags(including PG_locked) for tail pages folio = pfn_folio(softleaf_to_pfn(entry))
smp_wmb() VM_WARN_ON_ONCE(!folio_test_locked(folio))
prep_compound_page() for tail pages
In __split_folio_to_order(), smp_wmb() guarantees page flags of tail pages
are visible before the tail page becomes non-compound. smp_wmb() should
be paired with smp_rmb() in softleaf_to_folio(), which is missed. As a
result, if zap_nonpresent_ptes() accesses migration entry that stores tail
pfn, softleaf_to_folio() may see the updated compound_head of tail page
before page->flags.
This issue will trigger VM_WARN_ON_ONCE() in pfn_swap_entry_folio()
because of the race between folio split and zap_nonpresent_ptes()
leading to a folio incorrectly undergoing modification without a folio
lock being held.
This is a BUG_ON() before commit 93976a2034 ("mm: eliminate further
swapops predicates"), which in merged in v6.19-rc1.
To fix it, add missing smp_rmb() if the softleaf entry is migration entry
in softleaf_to_folio() and softleaf_to_page().
[tujinjiang@huawei.com: update function name and comments]
Link: https://lkml.kernel.org/r/20260321075214.3305564-1-tujinjiang@huawei.com
Link: https://lkml.kernel.org/r/20260319012541.4158561-1-tujinjiang@huawei.com
Fixes: e9b61f1985 ("thp: reintroduce split_huge_page()")
Signed-off-by: Jinjiang Tu <tujinjiang@huawei.com>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Cc: Barry Song <baohua@kernel.org>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nanyong Sun <sunnanyong@huawei.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Pull kvm fixes from Paolo Bonzini:
"ARM:
- Clear the pending exception state from a vcpu coming out of reset,
as it could otherwise affect the first instruction executed in the
guest
- Fix pointer arithmetic in address translation emulation, so that
the Hardware Access bit is set on the correct PTE instead of some
other location
s390:
- Fix deadlock in new memory management
- Properly handle kernel faults on donated memory
- Fix bounds checking for irq routing, with selftest
- Fix invalid machine checks and log all of them"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
KVM: arm64: Fix the descriptor address in __kvm_at_swap_desc()
KVM: s390: vsie: Avoid injecting machine check on signal
KVM: s390: log machine checks more aggressively
KVM: s390: selftests: Add IRQ routing address offset tests
KVM: s390: Limit adapter indicator access to mapped page
s390/mm: Add missing secure storage access fixups for donated memory
KVM: arm64: Discard PC update state on vcpu reset
KVM: s390: Fix a deadlock
Pull Compute Express Link (CXL) fixes from Dave Jiang:
- Adjust the startup priority of cxl_pmem to be higher than that of
cxl_acpi
- Use proper endpoint validity check upon sanitize
- Avoid incorrect DVSEC fallback when HDM decoders are enabled
- Fix CXL_ACPI and CXL_PMEM Kconfig tristate mismatch
- Fix leakage in __construct_region()
- Fix use after free of parent_port in cxl_detach_ep()
* tag 'cxl-fixes-7.0-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl:
cxl: Adjust the startup priority of cxl_pmem to be higher than that of cxl_acpi
cxl/mbox: Use proper endpoint validity check upon sanitize
cxl/hdm: Avoid incorrect DVSEC fallback when HDM decoders are enabled
cxl/acpi: Fix CXL_ACPI and CXL_PMEM Kconfig tristate mismatch
cxl/region: Fix leakage in __construct_region()
cxl/port: Fix use after free of parent_port in cxl_detach_ep()
KVM/arm64 fixes for 7.0, take #4
- Clear the pending exception state from a vcpu coming out of
reset, as it could otherwise affect the first instruction
executed in the guest.
- Fix the address translation emulation icode to set the Hardware
Access bit on the correct PTE instead of some other location.
Pull MM fixes from Andrew Morton:
"6 hotfixes. 2 are cc:stable. All are for MM.
All are singletons - please see the changelogs for details"
* tag 'mm-hotfixes-stable-2026-03-23-17-56' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm:
mm/damon/stat: monitor all System RAM resources
mm/zswap: add missing kunmap_local()
mailmap: update email address for Muhammad Usama Anjum
zram: do not slot_free() written-back slots
mm/damon/core: avoid use of half-online-committed context
mm/rmap: clear vma->anon_vma on error
Pull perf tools fixes from Arnaldo Carvalho de Melo:
- Fix parsing 'overwrite' in command line event definitions in
big-endian machines by writing correct union member
- Fix finding default metric in 'perf stat'
- Fix relative paths for including headers in 'perf kvm stat'
- Sync header copies with the kernel sources: msr-index.h, kvm,
build_bug.h
* tag 'perf-tools-fixes-for-v7.0-2-2026-03-23' of git://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools:
tools headers: Synchronize linux/build_bug.h with the kernel sources
tools headers UAPI: Sync x86's asm/kvm.h with the kernel sources
tools headers UAPI: Sync linux/kvm.h with the kernel sources
tools arch x86: Sync the msr-index.h copy with the kernel sources
perf kvm stat: Fix relative paths for including headers
perf parse-events: Fix big-endian 'overwrite' by writing correct union member
perf metricgroup: Fix metricgroup__has_metric_or_groups()
tools headers: Skip arm64 cputype.h check
Pull media fixes from Mauro Carvalho Chehab:
- rkvdec: fix stack usage with clang and improve handling missing
short/long term RPS
- synopsys: fix a Kconfig issue and an out-of-bounds check
- verisilicon: Fix kernel panic due to __initconst misuse
- media core: serialize REINIT and REQBUFS with req_queue_mutex
* tag 'media/v7.0-5' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media:
media: verisilicon: Fix kernel panic due to __initconst misuse
media: rkvdec: reduce stack usage in rkvdec_init_v4l2_vp9_count_tbl()
media: rkvdec: reduce excessive stack usage in assemble_hw_pps()
media: rkvdec: Improve handling missing short/long term RPS
media: mc, v4l2: serialize REINIT and REQBUFS with req_queue_mutex
media: synopsys: csi2rx: add missing kconfig dependency
media: synopsys: csi2rx: fix out-of-bounds check for formats array
Pull xen fixes from Juergen Gross:
"Restrict the xen privcmd driver in unprivileged domU to only allow
hypercalls to target domain when using secure boot"
* tag 'xsa482-7.0-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
xen/privcmd: add boot control for restricted usage in domU
xen/privcmd: restrict usage in unprivileged domU
DAMON_STAT usage document (Documentation/admin-guide/mm/damon/stat.rst)
says it monitors the system's entire physical memory. But, it is
monitoring only the biggest System RAM resource of the system. When there
are multiple System RAM resources, this results in monitoring only an
unexpectedly small fraction of the physical memory. For example, suppose
the system has a 500 GiB System RAM, 10 MiB non-System RAM, and 500 GiB
System RAM resources in order on the physical address space. DAMON_STAT
will monitor only the first 500 GiB System RAM. This situation is
particularly common on NUMA systems.
Select a physical address range that covers all System RAM areas of the
system, to fix this issue and make it work as documented.
[sj@kernel.org: return error if monitoring target region is invalid]
Link: https://lkml.kernel.org/r/20260317053631.87907-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20260316235118.873-1-sj@kernel.org
Fixes: 369c415e60 ("mm/damon: introduce DAMON_STAT module")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> [6.17+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Commit e2c3b6b21c ("mm: zswap: use SG list decompression APIs from
zsmalloc") updated zswap_decompress() to use the scatterwalk API to copy
data for uncompressed pages.
In doing so, it mapped kernel memory locally for 32-bit kernels using
kmap_local_folio(), however it never unmapped this memory.
This resulted in the linked syzbot report where a BUG_ON() is triggered
due to leaking the kmap slot.
This patch fixes the issue by explicitly unmapping the established kmap.
Also, add flush_dcache_folio() after the kunmap_local() call
I had assumed that a new folio here combined with the flush that is done at
the point of setting the PTE would suffice, but it doesn't seem that's
actually the case, as update_mmu_cache() will in many archtectures only
actually flush entries where a dcache flush was done on a range previously.
I had also wondered whether kunmap_local() might suffice, but it doesn't
seem to be the case.
Some arches do seem to actually dcache flush on unmap, parisc does it if
CONFIG_HIGHMEM is not set by setting ARCH_HAS_FLUSH_ON_KUNMAP and calling
kunmap_flush_on_unmap() from __kunmap_local(), otherwise non-CONFIG_HIGHMEM
callers do nothing here.
Otherwise arch_kmap_local_pre_unmap() is called which does:
* sparc - flush_cache_all()
* arm - if VIVT, __cpuc_flush_dcache_area()
* otherwise - nothing
Also arch_kmap_local_post_unmap() is called which does:
* arm - local_flush_tlb_kernel_page()
* csky - kmap_flush_tlb()
* microblaze, ppc - local_flush_tlb_page()
* mips - local_flush_tlb_one()
* sparc - flush_tlb_all() (again)
* x86 - arch_flush_lazy_mmu_mode()
* otherwise - nothing
But this is only if it's high memory, and doesn't cover all architectures,
so is presumably intended to handle other cache consistency concerns.
In any case, VIPT is problematic here whether low or high memory (in spite
of what the documentation claims, see [0] - 'the kernel did write to a page
that is in the page cache page and / or in high memory'), because dirty
cache lines may exist at the set indexed by the kernel direct mapping,
which won't exist in the set indexed by any subsequent userland mapping,
meaning userland might read stale data from L2 cache.
Even if the documentation is correct and low memory is fine not to be
flushed here, we can't be sure as to whether the memory is low or high
(kmap_local_folio() will be a no-op if low), and this call should be
harmless if it is low.
VIVT would require more work if the memory were shared and already mapped,
but this isn't the case here, and would anyway be handled by the dcache
flush call.
In any case, we definitely need this flush as far as I can tell.
And we should probably consider updating the documentation unless it turns
out there's somehow dcache synchronisation that happens for low
memory/64-bit kernels elsewhere?
[ljs@kernel.org: add flush_dcache_folio() after the kunmap_local() call]
Link: https://lkml.kernel.org/r/13e09a99-181f-45ac-a18d-057faf94bccb@lucifer.local
Link: https://lkml.kernel.org/r/20260316140122.339697-1-ljs@kernel.org
Link: https://docs.kernel.org/core-api/cachetlb.html [0]
Fixes: e2c3b6b21c ("mm: zswap: use SG list decompression APIs from zsmalloc")
Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Reported-by: syzbot+fe426bef95363177631d@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/69b75e2c.050a0220.12d28.015a.GAE@google.com
Acked-by: Yosry Ahmed <yosry@kernel.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: SeongJae Park <sj@kernel.org>
Acked-by: Yosry Ahmed <yosry@kernel.org>
Acked-by: Nhat Pham <nphamcs@gmail.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
To pick up the changes in:
6ffd853b0b ("build_bug.h: correct function parameters names in kernel-doc")
That just add some comments, addressing this perf tools build warning:
Warning: Kernel ABI header differences:
diff -u tools/include/linux/build_bug.h include/linux/build_bug.h
Please take a look at tools/include/uapi/README for further info on this
synchronization process.
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
To pick the changes in:
e2ffe85b6d ("KVM: x86: Introduce KVM_X86_QUIRK_VMCS12_ALLOW_FREEZE_IN_SMM")
That just rebuilds kvm-stat.c on x86, no change in functionality.
This silences these perf build warning:
Warning: Kernel ABI header differences:
diff -u tools/arch/x86/include/uapi/asm/kvm.h arch/x86/include/uapi/asm/kvm.h
Please see tools/include/uapi/README for further details.
Cc: Jim Mattson <jmattson@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
To pick the changes in:
da142f3d37 ("KVM: Remove subtle "struct kvm_stats_desc" pseudo-overlay")
That just rebuilds perf, as these patches don't add any new KVM ioctl to
be harvested for the 'perf trace' ioctl syscall argument beautifiers.
This addresses this perf build warning:
Warning: Kernel ABI header differences:
diff -u tools/include/uapi/linux/kvm.h include/uapi/linux/kvm.h
Please see tools/include/uapi/README for further details.
Cc: Sean Christopherson <seanjc@google.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
To pick up the changes from these csets:
9073428bb2 ("x86/sev: Allow IBPB-on-Entry feature for SNP guests")
That cause no changes to tooling as it doesn't include a new MSR to be
captured by the tools/perf/trace/beauty/tracepoints/x86_msr.sh script.
Just silences this perf build warning:
Warning: Kernel ABI header differences:
diff -u tools/arch/x86/include/asm/msr-index.h arch/x86/include/asm/msr-index.h
Cc: Borislav Petkov (AMD) <bp@alien8.de>
Cc: Kim Phillips <kim.phillips@amd.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Pull bpf fixes from Alexei Starovoitov:
- Fix how linked registers track zero extension of subregisters (Daniel
Borkmann)
- Fix unsound scalar fork for OR instructions (Daniel Wade)
- Fix exception exit lock check for subprogs (Ihor Solodrai)
- Fix undefined behavior in interpreter for SDIV/SMOD instructions
(Jenny Guanni Qu)
- Release module's BTF when module is unloaded (Kumar Kartikeya
Dwivedi)
- Fix constant blinding for PROBE_MEM32 instructions (Sachin Kumar)
- Reset register ID for END instructions to prevent incorrect value
tracking (Yazhou Tang)
* tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf:
selftests/bpf: Add a test cases for sync_linked_regs regarding zext propagation
bpf: Fix sync_linked_regs regarding BPF_ADD_CONST32 zext propagation
selftests/bpf: Add tests for maybe_fork_scalars() OR vs AND handling
bpf: Fix unsound scalar forking in maybe_fork_scalars() for BPF_OR
selftests/bpf: Add tests for sdiv32/smod32 with INT_MIN dividend
bpf: Fix undefined behavior in interpreter sdiv/smod for INT_MIN
selftests/bpf: Add tests for bpf_throw lock leak from subprogs
bpf: Fix exception exit lock checking for subprogs
bpf: Release module BTF IDR before module unload
selftests/bpf: Fix pkg-config call on static builds
bpf: Fix constant blinding for PROBE_MEM32 stores
selftests/bpf: Add test for BPF_END register ID reset
bpf: Reset register ID for BPF_END value tracking
Pull tracing fixes from Steven Rostedt:
- Revert "tracing: Remove pid in task_rename tracing output"
A change was made to remove the pid field from the task_rename event
because it was thought that it was always done for the current task
and recording the pid would be redundant. This turned out to be
incorrect and there are a few corner case where this is not true and
caused some regressions in tooling.
- Fix the reading from user space for migration
The reading of user space uses a seq lock type of logic where it uses
a per-cpu temporary buffer and disables migration, then enables
preemption, does the copy from user space, disables preemption,
enables migration and checks if there was any schedule switches while
preemption was enabled. If there was a context switch, then it is
considered that the per-cpu buffer could be corrupted and it tries
again. There's a protection check that tests if it takes a hundred
tries, it issues a warning and exits out to prevent a live lock.
This was triggered because the task was selected by the load balancer
to be migrated to another CPU, every time preemption is enabled the
migration task would schedule in try to migrate the task but can't
because migration is disabled and let it run again. This caused the
scheduler to schedule out the task every time it enabled preemption
and made the loop never exit (until the 100 iteration test
triggered).
Fix this by enabling and disabling preemption and keeping migration
enabled if the reading from user space needs to be done again. This
will let the migration thread migrate the task and the copy from user
space will likely pass on the next iteration.
- Fix trace_marker copy option freeing
The "copy_trace_marker" option allows a tracing instance to get a
copy of a write to the trace_marker file of the top level instance.
This is managed by a link list protected by RCU. When an instance is
removed, a check is made if the option is set, and if so
synchronized_rcu() is called.
The problem is that an iteration is made to reset all the flags to
what they were when the instance was created (to perform clean ups)
was done before the check of the copy_trace_marker option and that
option was cleared, so the synchronize_rcu() was never called.
Move the clearing of all the flags after the check of
copy_trace_marker to do synchronize_rcu() so that the option is still
set if it was before and the synchronization is performed.
- Fix entries setting when validating the persistent ring buffer
When validating the persistent ring buffer on boot up, the number of
events per sub-buffer is added to the sub-buffer meta page. The
validator was updating cpu_buffer->head_page (the first sub-buffer of
the per-cpu buffer) and not the "head_page" variable that was
iterating the sub-buffers. This was causing the first sub-buffer to
be assigned the entries for each sub-buffer and not the sub-buffer
that was supposed to be updated.
- Use "hash" value to update the direct callers
When updating the ftrace direct callers, it assigned a temporary
callback to all the callback functions of the ftrace ops and not just
the functions represented by the passed in hash. This causes an
unnecessary slow down of the functions of the ftrace_ops that is not
being modified. Only update the functions that are going to be
modified to call the ftrace loop function so that the update can be
made on those functions.
* tag 'trace-v7.0-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
ftrace: Use hash argument for tmp_ops in update_ftrace_direct_mod
ring-buffer: Fix to update per-subbuf entries of persistent ring buffer
tracing: Fix trace_marker copy link list updates
tracing: Fix failure to read user space from system call trace events
tracing: Revert "tracing: Remove pid in task_rename tracing output"
Pull i2c fixes from Wolfram Sang:
- fix broken I2C communication on Armada 3700 with recovery
- fix device_node reference leak in probe (fsi)
- fix NULL-deref when serial string is missing (cp2615)
* tag 'i2c-for-7.0-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
i2c: pxa: defer reset on Armada 3700 when recovery is used
i2c: fsi: Fix a potential leak in fsi_i2c_probe()
i2c: cp2615: fix serial string NULL-deref at probe
Pull x86 fixes from Ingo Molnar:
- Improve Qemu MCE-injection behavior by only using AMD SMCA MSRs if
the feature bit is set
- Fix the relative path of gettimeofday.c inclusion in vclock_gettime.c
- Fix a boot crash on UV clusters when a socket is marked as
'deconfigured' which are mapped to the SOCK_EMPTY node ID by
the UV firmware, while Linux APIs expect NUMA_NO_NODE.
The difference being (0xffff [unsigned short ~0]) vs [int -1]
* tag 'x86-urgent-2026-03-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/platform/uv: Handle deconfigured sockets
x86/entry/vdso: Fix path of included gettimeofday.c
x86/mce/amd: Check SMCA feature bit before accessing SMCA MSRs
Pull perf fixes from Ingo Molnar:
- Fix a PMU driver crash on AMD EPYC systems, caused by
a race condition in x86_pmu_enable()
- Fix a possible counter-initialization bug in x86_pmu_enable()
- Fix a counter inheritance bug in inherit_event() and
__perf_event_read()
- Fix an Intel PMU driver branch constraints handling bug
found by UBSAN
- Fix the Intel PMU driver's new Off-Module Response (OMR)
support code for Diamond Rapids / Nova lake, to fix a snoop
information parsing bug
* tag 'perf-urgent-2026-03-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/x86/intel: Fix OMR snoop information parsing issues
perf/x86/intel: Add missing branch counters constraint apply
perf: Make sure to use pmu_ctx->pmu for groups
x86/perf: Make sure to program the counter value for stopped events on migration
perf/x86: Move event pointer setup earlier in x86_pmu_enable()
Pull objtool fixes from Ingo Molnar:
"Fix three more livepatching related build environment bugs, and a
false positive warning with Clang jump tables"
* tag 'objtool-urgent-2026-03-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
objtool: Fix Clang jump table detection
livepatch/klp-build: Fix inconsistent kernel version
objtool/klp: fix mkstemp() failure with long paths
objtool/klp: fix data alignment in __clone_symbol()
Pull locking fix from Ingo Molnar:
"Fix a sparse build error regression in <linux/local_lock_internal.h>
caused by the locking context-analysis changes"
* tag 'locking-urgent-2026-03-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
include/linux/local_lock_internal.h: Make this header file again compatible with sparse
Pull irq fix from Ingo Molnar:
"Fix a mailbox channel leak in the riscv-rpmi-sysmsi irqchip driver"
* tag 'irq-urgent-2026-03-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
irqchip/riscv-rpmi-sysmsi: Fix mailbox channel leak in rpmi_sysmsi_probe()
slot_free() basically completely resets the slots by clearing all of
its flags and attributes. While zram_writeback_complete() restores
some of flags back (those that are necessary for async read
decompression) we still lose a lot of slot's metadata. For example,
slot's ac-time, or ZRAM_INCOMPRESSIBLE.
More importantly, restoring flags/attrs requires extra attention as
some of the flags are directly affecting zram device stats. And the
original code did not pay that attention. Namely ZRAM_HUGE slots
handling in zram_writeback_complete(). The call to slot_free() would
decrement ->huge_pages, however when zram_writeback_complete() restored
the slot's ZRAM_HUGE flag, it would not get reflected in an incremented
->huge_pages. So when the slot would finally get freed, slot_free()
would decrement ->huge_pages again, leading to underflow.
Fix this by open-coding the required memory free and stats updates in
zram_writeback_complete(), rather than calling the destructive
slot_free(). Since we now preserve the ZRAM_HUGE flag on written-back
slots (for the deferred decompression path), we also update slot_free()
to skip decrementing ->huge_pages if ZRAM_WB is set.
Link: https://lkml.kernel.org/r/20260320023143.2372879-1-senozhatsky@chromium.org
Link: https://lkml.kernel.org/r/20260319034912.1894770-1-senozhatsky@chromium.org
Fixes: d38fab605c ("zram: introduce compressed data writeback")
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Brian Geffon <bgeffon@google.com>
Cc: Richard Chang <richardycc@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
One major usage of damon_call() is online DAMON parameters update. It is
done by calling damon_commit_ctx() inside the damon_call() callback
function. damon_commit_ctx() can fail for two reasons: 1) invalid
parameters and 2) internal memory allocation failures. In case of
failures, the damon_ctx that attempted to be updated (commit destination)
can be partially updated (or, corrupted from a perspective), and therefore
shouldn't be used anymore. The function only ensures the damon_ctx object
can safely deallocated using damon_destroy_ctx().
The API callers are, however, calling damon_commit_ctx() only after
asserting the parameters are valid, to avoid damon_commit_ctx() fails due
to invalid input parameters. But it can still theoretically fail if the
internal memory allocation fails. In the case, DAMON may run with the
partially updated damon_ctx. This can result in unexpected behaviors
including even NULL pointer dereference in case of damos_commit_dests()
failure [1]. Such allocation failure is arguably too small to fail, so
the real world impact would be rare. But, given the bad consequence, this
needs to be fixed.
Avoid such partially-committed (maybe-corrupted) damon_ctx use by saving
the damon_commit_ctx() failure on the damon_ctx object. For this,
introduce damon_ctx->maybe_corrupted field. damon_commit_ctx() sets it
when it is failed. kdamond_call() checks if the field is set after each
damon_call_control->fn() is executed. If it is set, ignore remaining
callback requests and return. All kdamond_call() callers including
kdamond_fn() also check the maybe_corrupted field right after
kdamond_call() invocations. If the field is set, break the kdamond_fn()
main loop so that DAMON sill doesn't use the context that might be
corrupted.
[sj@kernel.org: let kdamond_call() with cancel regardless of maybe_corrupted]
Link: https://lkml.kernel.org/r/20260320031553.2479-1-sj@kernel.org
Link: https://sashiko.dev/#/patchset/20260319145218.86197-1-sj%40kernel.org
Link: https://lkml.kernel.org/r/20260319145218.86197-1-sj@kernel.org
Link: https://lore.kernel.org/20260319043309.97966-1-sj@kernel.org [1]
Fixes: 3301f1861d ("mm/damon/sysfs: handle commit command using damon_call()")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> [6.15+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Commit 542eda1a83 ("mm/rmap: improve anon_vma_clone(),
unlink_anon_vmas() comments, add asserts") alters the way errors are
handled, but overlooked one important aspect of clean up.
When a VMA encounters an error state in anon_vma_clone() (that is, on
attempted allocation of anon_vma_chain objects), it cleans up partially
established state in cleanup_partial_anon_vmas(), before returning an
error.
However, this occurs prior to anon_vma->num_active_vmas being incremented,
and it also fails to clear the VMA's vma->anon_vma field, which remains in
place.
This is immediately an inconsistent state, because
anon_vma->num_active_vmas is supposed to track the number of VMAs whose
vma->anon_vma field references that anon_vma, and now that count is
off-by-negative-1 for each VMA for which this error state has occurred.
When VMAs are unlinked from this anon_vma, unlink_anon_vmas() will
eventually underflow anon_vma->num_active_vmas, which will trigger a
warning.
This will always eventually happen, as we unlink anon_vma's at process
teardown.
It could also cause maybe_reuse_anon_vma() to incorrectly permit the reuse
of an anon_vma which has active VMAs attached, which will lead to a
persistently invalid state.
The solution is to clear the VMA's anon_vma field when we clean up partial
state, as the fact we are doing so indicates clearly that the VMA is not
correctly integrated into the anon_vma tree and thus this field is
invalid.
Link: https://lkml.kernel.org/r/20260318122632.63404-1-ljs@kernel.org
Fixes: 542eda1a83 ("mm/rmap: improve anon_vma_clone(), unlink_anon_vmas() comments, add asserts")
Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Reported-by: Sasha Levin <sashal@kernel.org>
Closes: https://lore.kernel.org/linux-mm/20260302151547.2389070-1-sashal@kernel.org/
Reported-by: Jiakai Xu <jiakaipeanut@gmail.com>
Closes: https://lore.kernel.org/linux-mm/CAFb8wJvRhatRD-9DVmr5v5pixTMPEr3UKjYBJjCd09OfH55CKg@mail.gmail.com/
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Acked-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Tested-by: Jiakai Xu <jiakaipeanut@gmail.com>
Acked-by: Harry Yoo <harry.yoo@oracle.com>
Cc: Jann Horn <jannh@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Sasha Levin (Microsoft) <sashal@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Pull driver core fixes from Danilo Krummrich:
- Generalize driver_override in the driver core, providing a common
sysfs implementation and concurrency-safe accessors for bus
implementations
- Do not use driver_override as IRQ name in the hwmon axi-fan driver
- Remove an unnecessary driver_override check in sh platform_early
- Migrate the platform bus to use the generic driver_override
infrastructure, fixing a UAF condition caused by accessing the
driver_override field without proper locking in the platform_match()
callback
* tag 'driver-core-7.0-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/driver-core/driver-core:
driver core: platform: use generic driver_override infrastructure
sh: platform_early: remove pdev->driver_override check
hwmon: axi-fan: don't use driver_override as IRQ name
docs: driver-model: document driver_override
driver core: generalize driver_override in struct device
The modify logic registers temporary ftrace_ops object (tmp_ops) to trigger
the slow path for all direct callers to be able to safely modify attached
addresses.
At the moment we use ops->func_hash for tmp_ops filter, which represents all
the systems attachments. It's faster to use just the passed hash filter, which
contains only the modified sites and is always a subset of the ops->func_hash.
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Menglong Dong <menglong8.dong@gmail.com>
Cc: Song Liu <song@kernel.org>
Link: https://patch.msgid.link/20260312123738.129926-1-jolsa@kernel.org
Fixes: e93672f770 ("ftrace: Add update_ftrace_direct_mod function")
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
When the "copy_trace_marker" option is enabled for an instance, anything
written into /sys/kernel/tracing/trace_marker is also copied into that
instances buffer. When the option is set, that instance's trace_array
descriptor is added to the marker_copies link list. This list is protected
by RCU, as all iterations uses an RCU protected list traversal.
When the instance is deleted, all the flags that were enabled are cleared.
This also clears the copy_trace_marker flag and removes the trace_array
descriptor from the list.
The issue is after the flags are called, a direct call to
update_marker_trace() is performed to clear the flag. This function
returns true if the state of the flag changed and false otherwise. If it
returns true here, synchronize_rcu() is called to make sure all readers
see that its removed from the list.
But since the flag was already cleared, the state does not change and the
synchronization is never called, leaving a possible UAF bug.
Move the clearing of all flags below the updating of the copy_trace_marker
option which then makes sure the synchronization is performed.
Also use the flag for checking the state in update_marker_trace() instead
of looking at if the list is empty.
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://patch.msgid.link/20260318185512.1b6c7db4@gandalf.local.home
Fixes: 7b382efd5e ("tracing: Allow the top level trace_marker to write into another instances")
Reported-by: Sasha Levin <sashal@kernel.org>
Closes: https://lore.kernel.org/all/20260225133122.237275-1-sashal@kernel.org/
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
The system call trace events call trace_user_fault_read() to read the user
space part of some system calls. This is done by grabbing a per-cpu
buffer, disabling migration, enabling preemption, calling
copy_from_user(), disabling preemption, enabling migration and checking if
the task was preempted while preemption was enabled. If it was, the buffer
is considered corrupted and it tries again.
There's a safety mechanism that will fail out of this loop if it fails 100
times (with a warning). That warning message was triggered in some
pi_futex stress tests. Enabling the sched_switch trace event and
traceoff_on_warning, showed the problem:
pi_mutex_hammer-1375 [006] d..21 138.981648: sched_switch: prev_comm=pi_mutex_hammer prev_pid=1375 prev_prio=95 prev_state=R+ ==> next_comm=migration/6 next_pid=47 next_prio=0
migration/6-47 [006] d..2. 138.981651: sched_switch: prev_comm=migration/6 prev_pid=47 prev_prio=0 prev_state=S ==> next_comm=pi_mutex_hammer next_pid=1375 next_prio=95
pi_mutex_hammer-1375 [006] d..21 138.981656: sched_switch: prev_comm=pi_mutex_hammer prev_pid=1375 prev_prio=95 prev_state=R+ ==> next_comm=migration/6 next_pid=47 next_prio=0
migration/6-47 [006] d..2. 138.981659: sched_switch: prev_comm=migration/6 prev_pid=47 prev_prio=0 prev_state=S ==> next_comm=pi_mutex_hammer next_pid=1375 next_prio=95
pi_mutex_hammer-1375 [006] d..21 138.981664: sched_switch: prev_comm=pi_mutex_hammer prev_pid=1375 prev_prio=95 prev_state=R+ ==> next_comm=migration/6 next_pid=47 next_prio=0
migration/6-47 [006] d..2. 138.981667: sched_switch: prev_comm=migration/6 prev_pid=47 prev_prio=0 prev_state=S ==> next_comm=pi_mutex_hammer next_pid=1375 next_prio=95
pi_mutex_hammer-1375 [006] d..21 138.981671: sched_switch: prev_comm=pi_mutex_hammer prev_pid=1375 prev_prio=95 prev_state=R+ ==> next_comm=migration/6 next_pid=47 next_prio=0
migration/6-47 [006] d..2. 138.981675: sched_switch: prev_comm=migration/6 prev_pid=47 prev_prio=0 prev_state=S ==> next_comm=pi_mutex_hammer next_pid=1375 next_prio=95
pi_mutex_hammer-1375 [006] d..21 138.981679: sched_switch: prev_comm=pi_mutex_hammer prev_pid=1375 prev_prio=95 prev_state=R+ ==> next_comm=migration/6 next_pid=47 next_prio=0
migration/6-47 [006] d..2. 138.981682: sched_switch: prev_comm=migration/6 prev_pid=47 prev_prio=0 prev_state=S ==> next_comm=pi_mutex_hammer next_pid=1375 next_prio=95
pi_mutex_hammer-1375 [006] d..21 138.981687: sched_switch: prev_comm=pi_mutex_hammer prev_pid=1375 prev_prio=95 prev_state=R+ ==> next_comm=migration/6 next_pid=47 next_prio=0
migration/6-47 [006] d..2. 138.981690: sched_switch: prev_comm=migration/6 prev_pid=47 prev_prio=0 prev_state=S ==> next_comm=pi_mutex_hammer next_pid=1375 next_prio=95
pi_mutex_hammer-1375 [006] d..21 138.981695: sched_switch: prev_comm=pi_mutex_hammer prev_pid=1375 prev_prio=95 prev_state=R+ ==> next_comm=migration/6 next_pid=47 next_prio=0
migration/6-47 [006] d..2. 138.981698: sched_switch: prev_comm=migration/6 prev_pid=47 prev_prio=0 prev_state=S ==> next_comm=pi_mutex_hammer next_pid=1375 next_prio=95
pi_mutex_hammer-1375 [006] d..21 138.981703: sched_switch: prev_comm=pi_mutex_hammer prev_pid=1375 prev_prio=95 prev_state=R+ ==> next_comm=migration/6 next_pid=47 next_prio=0
migration/6-47 [006] d..2. 138.981706: sched_switch: prev_comm=migration/6 prev_pid=47 prev_prio=0 prev_state=S ==> next_comm=pi_mutex_hammer next_pid=1375 next_prio=95
pi_mutex_hammer-1375 [006] d..21 138.981711: sched_switch: prev_comm=pi_mutex_hammer prev_pid=1375 prev_prio=95 prev_state=R+ ==> next_comm=migration/6 next_pid=47 next_prio=0
migration/6-47 [006] d..2. 138.981714: sched_switch: prev_comm=migration/6 prev_pid=47 prev_prio=0 prev_state=S ==> next_comm=pi_mutex_hammer next_pid=1375 next_prio=95
pi_mutex_hammer-1375 [006] d..21 138.981719: sched_switch: prev_comm=pi_mutex_hammer prev_pid=1375 prev_prio=95 prev_state=R+ ==> next_comm=migration/6 next_pid=47 next_prio=0
migration/6-47 [006] d..2. 138.981722: sched_switch: prev_comm=migration/6 prev_pid=47 prev_prio=0 prev_state=S ==> next_comm=pi_mutex_hammer next_pid=1375 next_prio=95
pi_mutex_hammer-1375 [006] d..21 138.981727: sched_switch: prev_comm=pi_mutex_hammer prev_pid=1375 prev_prio=95 prev_state=R+ ==> next_comm=migration/6 next_pid=47 next_prio=0
migration/6-47 [006] d..2. 138.981730: sched_switch: prev_comm=migration/6 prev_pid=47 prev_prio=0 prev_state=S ==> next_comm=pi_mutex_hammer next_pid=1375 next_prio=95
pi_mutex_hammer-1375 [006] d..21 138.981735: sched_switch: prev_comm=pi_mutex_hammer prev_pid=1375 prev_prio=95 prev_state=R+ ==> next_comm=migration/6 next_pid=47 next_prio=0
migration/6-47 [006] d..2. 138.981738: sched_switch: prev_comm=migration/6 prev_pid=47 prev_prio=0 prev_state=S ==> next_comm=pi_mutex_hammer next_pid=1375 next_prio=95
What happened was the task 1375 was flagged to be migrated. When
preemption was enabled, the migration thread woke up to migrate that task,
but failed because migration for that task was disabled. This caused the
loop to fail to exit because the task scheduled out while trying to read
user space.
Every time the task enabled preemption the migration thread would schedule
in, try to migrate the task, fail and let the task continue. But because
the loop would only enable preemption with migration disabled, it would
always fail because each time it enabled preemption to read user space,
the migration thread would try to migrate it.
To solve this, when the loop fails to read user space without being
scheduled out, enabled and disable preemption with migration enabled. This
will allow the migration task to successfully migrate the task and the
next loop should succeed to read user space without being scheduled out.
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://patch.msgid.link/20260316130734.1858a998@gandalf.local.home
Fixes: 64cf7d058a ("tracing: Have trace_marker use per-cpu data to read user space")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Add multiple test cases for linked register tracking with alu32 ops:
- Add a test that checks sync_linked_regs() regarding reg->id (the linked
target register) for BPF_ADD_CONST32 rather than known_reg->id (the
branch register).
- Add a test case for linked register tracking that exposes the cross-type
sync_linked_regs() bug. One register uses alu32 (w7 += 1, BPF_ADD_CONST32)
and another uses alu64 (r8 += 2, BPF_ADD_CONST64), both linked to the
same base register.
- Add a test case that exercises regsafe() path pruning when two execution
paths reach the same program point with linked registers carrying
different ADD_CONST flags (BPF_ADD_CONST32 from alu32 vs BPF_ADD_CONST64
from alu64). This particular test passes with and without the fix since
the pruning will fail due to different ranges, but it would still be
useful to carry this one as a regression test for the unreachable div
by zero.
With the fix applied all the tests pass:
# LDLIBS=-static PKG_CONFIG='pkg-config --static' ./vmtest.sh -- ./test_progs -t verifier_linked_scalars
[...]
./test_progs -t verifier_linked_scalars
#602/1 verifier_linked_scalars/scalars: find linked scalars:OK
#602/2 verifier_linked_scalars/sync_linked_regs_preserves_id:OK
#602/3 verifier_linked_scalars/scalars_neg:OK
#602/4 verifier_linked_scalars/scalars_neg_sub:OK
#602/5 verifier_linked_scalars/scalars_neg_alu32_add:OK
#602/6 verifier_linked_scalars/scalars_neg_alu32_sub:OK
#602/7 verifier_linked_scalars/scalars_pos:OK
#602/8 verifier_linked_scalars/scalars_sub_neg_imm:OK
#602/9 verifier_linked_scalars/scalars_double_add:OK
#602/10 verifier_linked_scalars/scalars_sync_delta_overflow:OK
#602/11 verifier_linked_scalars/scalars_sync_delta_overflow_large_range:OK
#602/12 verifier_linked_scalars/scalars_alu32_big_offset:OK
#602/13 verifier_linked_scalars/scalars_alu32_basic:OK
#602/14 verifier_linked_scalars/scalars_alu32_wrap:OK
#602/15 verifier_linked_scalars/scalars_alu32_zext_linked_reg:OK
#602/16 verifier_linked_scalars/scalars_alu32_alu64_cross_type:OK
#602/17 verifier_linked_scalars/scalars_alu32_alu64_regsafe_pruning:OK
#602/18 verifier_linked_scalars/alu32_negative_offset:OK
#602/19 verifier_linked_scalars/spurious_precision_marks:OK
#602 verifier_linked_scalars:OK
Summary: 1/19 PASSED, 0 SKIPPED, 0 FAILED
Co-developed-by: Puranjay Mohan <puranjay@kernel.org>
Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260319211507.213816-2-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Jenny reported that in sync_linked_regs() the BPF_ADD_CONST32 flag is
checked on known_reg (the register narrowed by a conditional branch)
instead of reg (the linked target register created by an alu32 operation).
Example case with reg:
1. r6 = bpf_get_prandom_u32()
2. r7 = r6 (linked, same id)
3. w7 += 5 (alu32 -- r7 gets BPF_ADD_CONST32, zero-extended by CPU)
4. if w6 < 0xFFFFFFFC goto safe (narrows r6 to [0xFFFFFFFC, 0xFFFFFFFF])
5. sync_linked_regs() propagates to r7 but does NOT call zext_32_to_64()
6. Verifier thinks r7 is [0x100000001, 0x100000004] instead of [1, 4]
Since known_reg above does not have BPF_ADD_CONST32 set above, zext_32_to_64()
is never called on alu32-derived linked registers. This causes the verifier
to track incorrect 64-bit bounds, while the CPU correctly zero-extends the
32-bit result.
The code checking known_reg->id was correct however (see scalars_alu32_wrap
selftest case), but the real fix needs to handle both directions - zext
propagation should be done when either register has BPF_ADD_CONST32, since
the linked relationship involves a 32-bit operation regardless of which
side has the flag.
Example case with known_reg (exercised also by scalars_alu32_wrap):
1. r1 = r0; w1 += 0x100 (alu32 -- r1 gets BPF_ADD_CONST32)
2. if r1 > 0x80 - known_reg = r1 (has BPF_ADD_CONST32), reg = r0 (doesn't)
Hence, fix it by checking for (reg->id | known_reg->id) & BPF_ADD_CONST32.
Moreover, sync_linked_regs() also has a soundness issue when two linked
registers used different ALU widths: one with BPF_ADD_CONST32 and the
other with BPF_ADD_CONST64. The delta relationship between linked registers
assumes the same arithmetic width though. When one register went through
alu32 (CPU zero-extends the 32-bit result) and the other went through
alu64 (no zero-extension), the propagation produces incorrect bounds.
Example:
r6 = bpf_get_prandom_u32() // fully unknown
if r6 >= 0x100000000 goto out // constrain r6 to [0, U32_MAX]
r7 = r6
w7 += 1 // alu32: r7.id = N | BPF_ADD_CONST32
r8 = r6
r8 += 2 // alu64: r8.id = N | BPF_ADD_CONST64
if r7 < 0xFFFFFFFF goto out // narrows r7 to [0xFFFFFFFF, 0xFFFFFFFF]
At the branch on r7, sync_linked_regs() runs with known_reg=r7
(BPF_ADD_CONST32) and reg=r8 (BPF_ADD_CONST64). The delta path
computes:
r8 = r7 + (delta_r8 - delta_r7) = 0xFFFFFFFF + (2 - 1) = 0x100000000
Then, because known_reg->id has BPF_ADD_CONST32, zext_32_to_64(r8) is
called, truncating r8 to [0, 0]. But r8 used a 64-bit ALU op -- the
CPU does NOT zero-extend it. The actual CPU value of r8 is
0xFFFFFFFE + 2 = 0x100000000, not 0. The verifier now underestimates
r8's 64-bit bounds, which is a soundness violation.
Fix sync_linked_regs() by skipping propagation when the two registers
have mixed ALU widths (one BPF_ADD_CONST32, the other BPF_ADD_CONST64).
Lastly, fix regsafe() used for path pruning: the existing checks used
"& BPF_ADD_CONST" to test for offset linkage, which treated
BPF_ADD_CONST32 and BPF_ADD_CONST64 as equivalent.
Fixes: 7a433e5193 ("bpf: Support negative offsets, BPF_SUB, and alu32 for linked register tracking")
Reported-by: Jenny Guanni Qu <qguanni@gmail.com>
Co-developed-by: Puranjay Mohan <puranjay@kernel.org>
Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260319211507.213816-1-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Daniel Wade says:
====================
bpf: Fix unsound scalar forking for BPF_OR
maybe_fork_scalars() unconditionally sets the pushed path dst register
to 0 for both BPF_AND and BPF_OR. For AND this is correct (0 & K == 0),
but for OR it is wrong (0 | K == K, not 0). This causes the verifier to
track an incorrect value on the pushed path, leading to a verifier/runtime
divergence that allows out-of-bounds map value access.
v4: Use block comment style for multi-line comments in selftests (Amery Hung)
Add Reviewed-by/Acked-by tags
v3: Use single-line comment style in selftests (Alexei Starovoitov)
v2: Use push_stack(env, env->insn_idx, ...) to re-execute the insn
on the pushed path (Eduard Zingerman)
====================
Link: https://patch.msgid.link/20260314021521.128361-1-danjwade95@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add three test cases to verifier_bounds.c to verify that
maybe_fork_scalars() correctly tracks register values for BPF_OR
operations with constant source operands:
1. or_scalar_fork_rejects_oob: After ARSH 63 + OR 8, the pushed
path should have dst = 8. With value_size = 8, accessing
map_value + 8 is out of bounds and must be rejected.
2. and_scalar_fork_still_works: Regression test ensuring AND
forking continues to work. ARSH 63 + AND 4 produces pushed
dst = 0 and current dst = 4, both within value_size = 8.
3. or_scalar_fork_allows_inbounds: After ARSH 63 + OR 4, the
pushed path has dst = 4, which is within value_size = 8
and should be accepted.
These tests exercise the fix in the previous patch, which makes the
pushed path re-execute the ALU instruction so it computes the correct
result for BPF_OR.
Signed-off-by: Daniel Wade <danjwade95@gmail.com>
Reviewed-by: Amery Hung <ameryhung@gmail.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260314021521.128361-3-danjwade95@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
maybe_fork_scalars() is called for both BPF_AND and BPF_OR when the
source operand is a constant. When dst has signed range [-1, 0], it
forks the verifier state: the pushed path gets dst = 0, the current
path gets dst = -1.
For BPF_AND this is correct: 0 & K == 0.
For BPF_OR this is wrong: 0 | K == K, not 0.
The pushed path therefore tracks dst as 0 when the runtime value is K,
producing an exploitable verifier/runtime divergence that allows
out-of-bounds map access.
Fix this by passing env->insn_idx (instead of env->insn_idx + 1) to
push_stack(), so the pushed path re-executes the ALU instruction with
dst = 0 and naturally computes the correct result for any opcode.
Fixes: bffacdb80b ("bpf: Recognize special arithmetic shift in the verifier")
Signed-off-by: Daniel Wade <danjwade95@gmail.com>
Reviewed-by: Amery Hung <ameryhung@gmail.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260314021521.128361-2-danjwade95@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Jenny Guanni Qu says:
====================
bpf: Fix abs(INT_MIN) undefined behavior in interpreter sdiv/smod
The BPF interpreter's signed 32-bit division and modulo handlers use
abs() on s32 operands, which is undefined for S32_MIN. This causes
the interpreter to compute wrong results, creating a mismatch with
the verifier's range tracking.
For example, INT_MIN / 2 returns 0x40000000 instead of the correct
0xC0000000. The verifier tracks the correct range, so a crafted BPF
program can exploit the mismatch for out-of-bounds map value access
(confirmed by KASAN).
Patch 1 introduces abs_s32() which handles S32_MIN correctly and
replaces all 8 abs((s32)...) call sites. s32 is the only affected
case -- the s64 handlers do not use abs().
Patch 2 adds selftests covering sdiv32 and smod32 with INT_MIN
dividend to prevent regression.
Changes since v4:
- Renamed __safe_abs32() to abs_s32() and dropped inline keyword
per Alexei Starovoitov's feedback
Changes since v3:
- Fixed stray blank line deletion in the file header
- Improved comment per Yonghong Song's suggestion
- Added JIT vs interpreter context to selftest commit message
Changes since v2:
- Simplified to use -(u32)x per Mykyta Yatsenko's suggestion
Changes since v1:
- Moved helper above kerneldoc comment block to fix build warnings
====================
Link: https://patch.msgid.link/20260311011116.2108005-1-qguanni@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add tests to verify that signed 32-bit division and modulo operations
produce correct results when the dividend is INT_MIN (0x80000000).
The bug fixed in the previous commit only affects the BPF interpreter
path. When JIT is enabled (the default on most architectures), the
native CPU division instruction produces the correct result and these
tests pass regardless. With bpf_jit_enable=0, the interpreter is used
and without the previous fix, INT_MIN / 2 incorrectly returns
0x40000000 instead of 0xC0000000 due to abs(S32_MIN) undefined
behavior, causing these tests to fail.
Test cases:
- SDIV32 INT_MIN / 2 = -1073741824 (imm and reg divisor)
- SMOD32 INT_MIN % 2 = 0 (positive and negative divisor)
Reviewed-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Jenny Guanni Qu <qguanni@gmail.com>
Link: https://lore.kernel.org/r/20260311011116.2108005-3-qguanni@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The BPF interpreter's signed 32-bit division and modulo handlers use
the kernel abs() macro on s32 operands. The abs() macro documentation
(include/linux/math.h) explicitly states the result is undefined when
the input is the type minimum. When DST contains S32_MIN (0x80000000),
abs((s32)DST) triggers undefined behavior and returns S32_MIN unchanged
on arm64/x86. This value is then sign-extended to u64 as
0xFFFFFFFF80000000, causing do_div() to compute the wrong result.
The verifier's abstract interpretation (scalar32_min_max_sdiv) computes
the mathematically correct result for range tracking, creating a
verifier/interpreter mismatch that can be exploited for out-of-bounds
map value access.
Introduce abs_s32() which handles S32_MIN correctly by casting to u32
before negating, avoiding signed overflow entirely. Replace all 8
abs((s32)...) call sites in the interpreter's sdiv32/smod32 handlers.
s32 is the only affected case -- the s64 division/modulo handlers do
not use abs().
Fixes: ec0e2da95f ("bpf: Support new signed div/mod instructions.")
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Mykyta Yatsenko <yatsenko@meta.com>
Signed-off-by: Jenny Guanni Qu <qguanni@gmail.com>
Link: https://lore.kernel.org/r/20260311011116.2108005-2-qguanni@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add test cases to ensure the verifier correctly rejects bpf_throw from
subprogs when RCU, preempt, or IRQ locks are held:
* reject_subprog_rcu_lock_throw: subprog acquires bpf_rcu_read_lock and
then calls bpf_throw
* reject_subprog_throw_preempt_lock: always-throwing subprog called while
caller holds bpf_preempt_disable
* reject_subprog_throw_irq_lock: always-throwing subprog called while
caller holds bpf_local_irq_save
Assisted-by: Claude:claude-opus-4-6
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260320000809.643798-2-ihor.solodrai@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
