The WCH CH334/CH335[0] are USB2.0 protocol compliant 4-port USB HUB
controller chips, supporting USB2.0 high-speed and full-speed for
upstream ports, and USB2.0 high-speed 480Mbps, full-speed 12Mbps and
low-speed 1.5Mbps for downstream ports, supporting not only low-cost STT
mode (single TT schedules 4 downstream ports in time share), but also
supports high performance MTT mode (4 TTs each corresponding to 1 port,
concurrent processing).
[0]: https://www.wch-ic.com/downloads/CH334DS1_PDF.html
Signed-off-by: Chaoyi Chen <chaoyi.chen@rock-chips.com>
Link: https://patch.msgid.link/20260113095827.115-3-kernel@airkyi.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The WCH CH334/CH335[0] are USB2.0 protocol compliant 4-port USB HUB
controller chips, supporting USB2.0 high-speed and full-speed for
upstream ports, and USB2.0 high-speed 480Mbps, full-speed 12Mbps and
low-speed 1.5Mbps for downstream ports, supporting not only low-cost STT
mode (single TT schedules 4 downstream ports in time share), but also
supports high performance MTT mode (4 TTs each corresponding to 1 port,
concurrent processing).
Add a device tree binding for it.
[0]: https://www.wch-ic.com/downloads/CH334DS1_PDF.html
Signed-off-by: Chaoyi Chen <chaoyi.chen@rock-chips.com>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://patch.msgid.link/20260113095827.115-2-kernel@airkyi.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The ChipIdea UDC driver can encounter "not page aligned sg buffer"
errors when a USB device is reconnected after being disconnected
during an active transfer. This occurs because _ep_nuke() returns
requests to the gadget layer without properly unmapping DMA buffers
or cleaning up scatter-gather bounce buffers.
Root cause:
When a disconnect happens during a multi-segment DMA transfer, the
request's num_mapped_sgs field and sgt.sgl pointer remain set with
stale values. The request is returned to the gadget driver with status
-ESHUTDOWN but still has active DMA state. If the gadget driver reuses
this request on reconnect without reinitializing it, the stale DMA
state causes _hardware_enqueue() to skip DMA mapping (seeing non-zero
num_mapped_sgs) and attempt to use freed/invalid DMA addresses,
leading to alignment errors and potential memory corruption.
The normal completion path via _hardware_dequeue() properly calls
usb_gadget_unmap_request_by_dev() and sglist_do_debounce() before
returning the request. The _ep_nuke() path must do the same cleanup
to ensure requests are returned in a clean, reusable state.
Fix:
Add DMA unmapping and bounce buffer cleanup to _ep_nuke() to mirror
the cleanup sequence in _hardware_dequeue():
- Call usb_gadget_unmap_request_by_dev() if num_mapped_sgs is set
- Call sglist_do_debounce() with copy=false if bounce buffer exists
This ensures that when requests are returned due to endpoint shutdown,
they don't retain stale DMA mappings. The 'false' parameter to
sglist_do_debounce() prevents copying data back (appropriate for
shutdown path where transfer was aborted).
Signed-off-by: Mario Peter <mario.peter@leica-geosystems.com>
Reviewed-by: Xu Yang <xu.yang_2@nxp.com>
Acked-by: Peter Chen <peter.chen@kernel.org>
Link: https://patch.msgid.link/20260108165902.795354-1-mario.peter@leica-geosystems.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Do dwc3 core auto suspend enable for device and disable for host
, this can make sure dwc3 core device auto suspend setting is
correct all the time, the background of disable dwc3 core device
auto suspend is to make its parent device suspend immediately
(so wakeup enable can be enabled) after xhci-plat device suspended,
for device mode, we keep the dwc3 core device auto suspend is to
give some wait for gadget to be enumerated.
Note: It's a temporary solution until we switch to using the new
flatten model.
Acked-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Signed-off-by: Xu Yang <xu.yang_2@nxp.com>
Link: https://patch.msgid.link/20260108081433.2119328-3-xu.yang_2@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Currently, DMA_FROM_DEVICE is used when attaching DMABUFs to IN
endpoints and DMA_TO_DEVICE for OUT endpoints. This is inverted from
how it should be.
The result is IOMMU read-only mappings placed on OUT queues,
triggering arm-smmu write faults.
Put differently, OUT endpoints flow data from host -> gadget, meaning
the UDC peripheral needs to have write access to the buffer to fill it
with the incoming data.
This commit flips the directions and updates the implicit-sync helpers
so IN endpoints act as readers and OUT endpoints as writers.
Signed-off-by: Sam Day <me@samcday.com>
Tested-by: David Heidelberg <david@ixit.cz> # OnePlus 6T on sdm845-next-20251119
Link: https://patch.msgid.link/20260108-ffs-dmabuf-ioctl-fix-v1-2-e51633891a81@samcday.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When ffs_epfile_ioctl handles FUNCTIONFS_DMABUF_* ioctls, it's currently
falling through when copy_from_user fails.
However, this fallthrough isn't being checked properly, so the handler
continues executing further than it should. It then tries the secondary
dispatch where it ultimately gives up and returns -ENOTTY.
The end result is invalid ioctl invocations will yield a -ENOTTY rather
than an -EFAULT.
It's a common pattern elsewhere in the kernel code to directly return
-EFAULT when copy_from_user fails. So we update ffs_epfile_ioctl to do
the same and fix this issue.
Signed-off-by: Sam Day <me@samcday.com>
Link: https://patch.msgid.link/20260108-ffs-dmabuf-ioctl-fix-v1-1-e51633891a81@samcday.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In usbg_submit_command(), which handles the UAS protocol, the 'data_len'
member of the 'usbg_cmd' structure was left uninitialized by the
logic, relying instead on the zeroing performed by usbg_get_cmd().
In contrast, the BOT path (bot_submit_command) explicitly initializes
this field from the Command Block Wrapper (CBW). This discrepancy is
evident in error handling paths where __target_init_cmd() is called
using cmd->data_len.
Explicitly initialize cmd->data_len to 0 in the UAS path and use this
variable when calling target_submit_cmd(). This ensures architectural
consistency between the UAS and BOT protocols within the driver and
avoids reliance on implicit memory state during error transitions.
Signed-off-by: Jiasheng Jiang <jiashengjiangcool@gmail.com>
Link: https://patch.msgid.link/20260107190622.26070-1-jiashengjiangcool@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Currently, the net_device is allocated in ncm_alloc_inst() and freed in
ncm_free_inst(). This ties the network interface's lifetime to the
configuration instance rather than the USB connection (bind/unbind).
This decoupling causes issues when the USB gadget is disconnected where
the underlying gadget device is removed. The net_device can outlive its
parent, leading to dangling sysfs links and NULL pointer dereferences
when accessing the freed gadget device.
Problem 1: NULL pointer dereference on disconnect
Unable to handle kernel NULL pointer dereference at virtual address
0000000000000000
Call trace:
__pi_strlen+0x14/0x150
rtnl_fill_ifinfo+0x6b4/0x708
rtmsg_ifinfo_build_skb+0xd8/0x13c
rtmsg_ifinfo+0x50/0xa0
__dev_notify_flags+0x4c/0x1f0
dev_change_flags+0x54/0x70
do_setlink+0x390/0xebc
rtnl_newlink+0x7d0/0xac8
rtnetlink_rcv_msg+0x27c/0x410
netlink_rcv_skb+0x134/0x150
rtnetlink_rcv+0x18/0x28
netlink_unicast+0x254/0x3f0
netlink_sendmsg+0x2e0/0x3d4
Problem 2: Dangling sysfs symlinks
console:/ # ls -l /sys/class/net/ncm0
lrwxrwxrwx ... /sys/class/net/ncm0 ->
/sys/devices/platform/.../gadget.0/net/ncm0
console:/ # ls -l /sys/devices/platform/.../gadget.0/net/ncm0
ls: .../gadget.0/net/ncm0: No such file or directory
Move the net_device allocation to ncm_bind() and deallocation to
ncm_unbind(). This ensures the network interface exists only when the
gadget function is actually bound to a configuration.
To support pre-bind configuration (e.g., setting interface name or MAC
address via configfs), cache user-provided options in f_ncm_opts
using the gether_opts structure. Apply these cached settings to the
net_device upon creation in ncm_bind().
Preserve the use-after-free fix from commit 6334b8e455 ("usb: gadget:
f_ncm: Fix UAF ncm object at re-bind after usb ep transport error").
Check opts->net in ncm_set_alt() and ncm_disable() to ensure
gether_disconnect() runs only if a connection was established.
Fixes: 40d133d7f5 ("usb: gadget: f_ncm: convert to new function interface with backward compatibility")
Cc: stable@kernel.org
Signed-off-by: Kuen-Han Tsai <khtsai@google.com>
Link: https://patch.msgid.link/20251230-ncm-refactor-v1-3-793e347bc7a7@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The net_device in the u_ether framework currently requires explicit
calls to unregister and free the device.
Introduce gether_unregister_free_netdev() and the corresponding
auto-cleanup macro. This ensures that if a net_device is registered, it
is properly unregistered and the associated work queue is flushed before
the memory is freed.
This is a preparatory patch to simplify error handling paths in gadget
drivers by removing the need for explicit goto labels for net_device
cleanup.
Signed-off-by: Kuen-Han Tsai <khtsai@google.com>
Link: https://patch.msgid.link/20251230-ncm-refactor-v1-2-793e347bc7a7@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Currently, the net_device is allocated when the function instance is
created (e.g., in ncm_alloc_inst()). While this allows userspace to
configure the device early, it decouples the net_device lifecycle from
the actual USB connection state (bind/unbind). The goal is to defer
net_device creation to the bind callback to properly align the lifecycle
with its parent gadget device.
However, deferring net_device allocation would prevent userspace from
configuring parameters (like interface name or MAC address) before the
net_device exists.
Introduce a new structure, struct gether_opts, associated with the
usb_function_instance, to cache settings independently of the
net_device. These settings include the interface name pattern, MAC
addresses (device and host), queue multiplier, and address assignment
type.
New helper functions are added:
- gether_setup_opts_default(): Initializes struct gether_opts with
defaults, including random MAC addresses.
- gether_apply_opts(): Applies the cached options from a struct
gether_opts to a valid net_device.
To expose these options to userspace, new configfs macros
(USB_ETHER_OPTS_ITEM and USB_ETHER_OPTS_ATTR_*) are defined in
u_ether_configfs.h. These attributes are part of the function
instance's configfs group.
This refactoring is a preparatory step. It allows the subsequent patch
to safely move the net_device allocation from the instance creation
phase to the bind phase without losing the ability to pre-configure
the interface via configfs.
Signed-off-by: Kuen-Han Tsai <khtsai@google.com>
Link: https://patch.msgid.link/20251230-ncm-refactor-v1-1-793e347bc7a7@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Pull USB fixes from Greg KH:
"Here are some small USB fixes, and bunch of reverts for 6.19-rc3.
Included in here are:
- reverts of some typec ucsi driver changes that had a lot of
regression reports after -rc1. Let's just revert it all for now and
it will come back in a way that is better tested.
- other typec bugfixes
- usb-storage quirk fixups
- dwc3 driver fix
- other minor USB fixes for reported problems.
All of these have passed 0-day testing and individual testing"
* tag 'usb-6.19-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb: (22 commits)
Revert "usb: typec: ucsi: Update UCSI structure to have message in and message out fields"
Revert "usb: typec: ucsi: Add support for message out data structure"
Revert "usb: typec: ucsi: Enable debugfs for message_out data structure"
Revert "usb: typec: ucsi: Add support for SET_PDOS command"
Revert "usb: typec: ucsi: Fix null pointer dereference in ucsi_sync_control_common"
Revert "usb: typec: ucsi: Get connector status after enable notifications"
usb: ohci-nxp: clean up probe error labels
usb: gadget: lpc32xx_udc: clean up probe error labels
usb: ohci-nxp: fix device leak on probe failure
usb: phy: isp1301: fix non-OF device reference imbalance
usb: gadget: lpc32xx_udc: fix clock imbalance in error path
usb: typec: ucsi: Get connector status after enable notifications
usb: usb-storage: Maintain minimal modifications to the bcdDevice range.
usb: dwc3: of-simple: fix clock resource leak in dwc3_of_simple_probe
usb: typec: ucsi: Fix null pointer dereference in ucsi_sync_control_common
USB: lpc32xx_udc: Fix error handling in probe
usb: typec: altmodes/displayport: Drop the device reference in dp_altmode_probe()
usb: phy: fsl-usb: Fix use-after-free in delayed work during device removal
usb: renesas_usbhs: Fix a resource leak in usbhs_pipe_malloc()
usb: typec: ucsi: huawei-gaokin: add DRM dependency
...
Pull serial driver fixes from Greg KH:
"Here are some small serial driver fixes for some reported issues.
Included in here are:
- serial sysfs fwnode fix that was much reported
- sh-sci driver fix
- serial device init bugfix
- 8250 bugfix
- xilinx_uartps bugfix
All of these have passed 0-day testing and individual testing"
* tag 'tty-6.19-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
serial: xilinx_uartps: fix rs485 delay_rts_after_send
serial: sh-sci: Check that the DMA cookie is valid
serial: core: Fix serial device initialization
serial: 8250: longson: Fix NULL vs IS_ERR() bug in probe
serial: core: Restore sysfs fwnode information
Pull firewire fix from Takashi Sakamoto:
"A fix for PCI driver for Texas Instruments PCILyx series.
The driver had a bug where it allocated a DMA-coherent buffer of 16 KB
but released it using PAGE_SIZE. This disproportion was reported in
2020, but the fix was never merged. It is finally resolved"
* tag 'firewire-fixes-6.19-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394:
firewire: nosy: Fix dma_free_coherent() size
Pull RISC-V updates from Paul Walmsley:
"Nothing exotic here; these are the cleanup and new ISA extension
probing patches (not including CFI):
- Add probing and userspace reporting support for the standard RISC-V
ISA extensions Zilsd and Zclsd, which implement load/store dual
instructions on RV32
- Abstract the register saving code in setup_sigcontext() so it can
be used for stateful RISC-V ISA extensions beyond the vector
extension
- Add the SBI extension ID and some initial data structure
definitions for the RISC-V standard SBI debug trigger extension
- Clean up some code slightly: change some page table functions to
avoid atomic operations oinn !SMP and to avoid unnecessary casts to
atomic_long_t; and use the existing RISCV_FULL_BARRIER macro in
place of some open-coded 'fence rw,rw' instructions"
* tag 'riscv-for-linus-6.19-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
riscv: Add SBI debug trigger extension and function ids
riscv/atomic.h: use RISCV_FULL_BARRIER in _arch_atomic* function.
riscv: hwprobe: export Zilsd and Zclsd ISA extensions
riscv: add ISA extension parsing for Zilsd and Zclsd
dt-bindings: riscv: add Zilsd and Zclsd extension descriptions
riscv: mm: use xchg() on non-atomic_long_t variables, not atomic_long_xchg()
riscv: mm: ptep_get_and_clear(): avoid atomic ops when !CONFIG_SMP
riscv: mm: pmdp_huge_get_and_clear(): avoid atomic ops when !CONFIG_SMP
riscv: signal: abstract header saving for setup_sigcontext
Pull powerpc fixes from Madhavan Srinivasan:
- Fix for kexec warning due to SMT disable or partial SMT enabled
- Handle font bitmap pointer with reloc_offset to fix boot crash
- Fix to enable cpuidle state for Power11
- Couple of misc fixes
Thanks to Aboorva Devarajan, Aditya Bodkhe, Cedar Maxwell, Christian
Zigotzky, Christophe Leroy, Christophe Leroy (CS GROUP), Finn Thain,
Gopi Krishna Menon, Guenter Roeck, Jan Stancek, Joe Lawrence, Josh
Poimboeuf, Justin M. Forbes, Madadi Vineeth Reddy, Naveen N Rao (AMD),
Nysal Jan K.A., Sachin P Bappalige, Samir M, Sourabh Jain, Srikar
Dronamraju, and Stan Johnson
* tag 'powerpc-6.19-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
powerpc/32: Restore disabling of interrupts at interrupt/syscall exit
powerpc/powernv: Enable cpuidle state detection for POWER11
powerpc: Add reloc_offset() to font bitmap pointer used for bootx_printf()
powerpc/tools: drop `-o pipefail` in gcc check scripts
selftests/powerpc/pmu/: Add check_extended_reg_test to .gitignore
powerpc/kexec: Enable SMT before waking offline CPUs
Pull spi fixes from Mark Brown:
"We've got more fixes here for the Cadence QSPI controller, this time
fixing some issues that come up when working with slower flashes on
some platforms plus a general race condition.
We also add support for the Allwinner A523, this is just some new
compatibles"
* tag 'spi-fix-v6.19-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi:
spi: cadence-quadspi: Improve CQSPI_SLOW_SRAM quirk if flash is slow
spi: cadence-quadspi: Prevent lost complete() call during indirect read
spi: sun6i: Support A523's SPI controllers
spi: dt-bindings: sun6i: Add compatibles for A523's SPI controllers
Pull regulator fixes from Mark Brown:
"A couple of fixes from Thomas, making the UAPI headers more robustly
correct and ensuring they are covered by checkpatch, and one from
Andreas fixing an update for a change to the DT bindings that I missed
was requested during bindings review in the newly added fp9931 driver"
* tag 'regulator-fix-v6.19-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator:
regulator: fp9931: fix regulator node pointer
regulator: Add UAPI headers to MAINTAINERS
regulator: uapi: Use UAPI integer type
Pull SCSI fixes from James Bottomley:
"Three HBA driver and one upper level driver (sg) fix.
The sg change is the largest, but that results mostly from moving code
to avoid the described race condition"
* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
scsi: ufs: core: Add ufshcd_update_evt_hist() for UFS suspend error
scsi: sg: Fix occasional bogus elapsed time that exceeds timeout
scsi: mpi3mr: Read missing IOCFacts flag for reply queue full overflow
scsi: scsi_debug: Fix atomic write enable module param description
Pull smb client fix from Steve French:
- Fix potential memory leak
* tag 'v6.19-rc2-smb3-client-fix' of git://git.samba.org/sfrench/cifs-2.6:
cifs: Fix memory and information leak in smb3_reconfigure()
Pull driver core fixes from Danilo Krummrich:
- Introduce DMA Rust helpers to avoid build errors when !CONFIG_HAS_DMA
- Remove unnecessary (and hence incorrect) endian conversion in the
Rust PCI driver sample code
- Fix memory leak in the unwind path of debugfs_change_name()
- Support non-const struct software_node pointers in
SOFTWARE_NODE_REFERENCE(), after introducing _Generic()
- Avoid NULL pointer dereference in the unwind path of
simple_xattrs_free()
* tag 'driver-core-6.19-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/driver-core/driver-core:
fs/kernfs: null-ptr deref in simple_xattrs_free()
software node: Also support referencing non-constant software nodes
debugfs: Fix memleak in debugfs_change_name().
samples: rust: fix endianness issue in rust_driver_pci
rust: dma: add helpers for architectures without CONFIG_HAS_DMA
Pull EFI fixes from Ard Biesheuvel:
"A couple of fixes for EFI regressions introduced this cycle:
- Make EDID handling in the EFI stub mixed mode safe
- Ensure that efi_mm.user_ns has a sane value - this is needed now
that EFI runtime calls are preemptible on arm64"
* tag 'efi-fixes-for-v6.19-1' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi:
kthread: Warn if mm_struct lacks user_ns in kthread_use_mm()
arm64: efi: Fix NULL pointer dereference by initializing user_ns
efi/libstub: gop: Fix EDID support in mixed-mode
Pull block fixes from Jens Axboe:
- Fix for a signedness issue introduced in this kernel release for rnbd
- Fix up user copy references for ublk when the server exits
* tag 'block-6.19-20251226' of git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux:
block: rnbd-clt: Fix signedness bug in init_dev()
ublk: clean up user copy references on ublk server exit
Pull io_uring fix from Jens Axboe:
"Just a single fix for a bug that can cause a leak of the filename with
IORING_OP_OPENAT, if direct descriptors are asked for and O_CLOEXEC
has been set in the request flags"
* tag 'io_uring-6.19-20251226' of git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux:
io_uring: fix filename leak in __io_openat_prep()
Pull virtio fixes from Michael Tsirkin:
"Just a bunch of fixes, mostly trivial ones in tools/virtio"
* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost:
vhost/vsock: improve RCU read sections around vhost_vsock_get()
tools/virtio: add device, device_driver stubs
tools/virtio: fix up oot build
virtio_features: make it self-contained
tools/virtio: switch to kernel's virtio_config.h
tools/virtio: stub might_sleep and synchronize_rcu
tools/virtio: add struct cpumask to cpumask.h
tools/virtio: pass KCFLAGS to module build
tools/virtio: add ucopysize.h stub
tools/virtio: add dev_WARN_ONCE and is_vmalloc_addr stubs
tools/virtio: stub DMA mapping functions
tools/virtio: add struct module forward declaration
tools/virtio: use kernel's virtio.h
virtio: make it self-contained
tools/virtio: fix up compiler.h stub
Pull smb server fixes from Steve French:
- Fix parsing of SMB1 negotiate request by adjusting offsets affected
by the removal of the RFC1002 length field from the SMB header
- Update minimum PDU size macros for both SMB1 and SMB2
- Rename smb2_get_msg function to smb_get_msg to better reflect its
role in handling both SMB1 and SMB2 requests
* tag 'v6.19-rc2-smb3-server-fixes' of git://git.samba.org/ksmbd:
smb/server: fix minimum SMB2 PDU size
smb/server: fix minimum SMB1 PDU size
ksmbd: rename smb2_get_msg to smb_get_msg
ksmbd: Fix to handle removal of rfc1002 header from smb_hdr
__io_openat_prep() allocates a struct filename using getname(). However,
for the condition of the file being installed in the fixed file table as
well as having O_CLOEXEC flag set, the function returns early. At that
point, the request doesn't have REQ_F_NEED_CLEANUP flag set. Due to this,
the memory for the newly allocated struct filename is not cleaned up,
causing a memory leak.
Fix this by setting the REQ_F_NEED_CLEANUP for the request just after the
successful getname() call, so that when the request is torn down, the
filename will be cleaned up, along with other resources needing cleanup.
Reported-by: syzbot+00e61c43eb5e4740438f@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=00e61c43eb5e4740438f
Tested-by: syzbot+00e61c43eb5e4740438f@syzkaller.appspotmail.com
Cc: stable@vger.kernel.org
Signed-off-by: Prithvi Tambewagh <activprithvi@gmail.com>
Fixes: b9445598d8 ("io_uring: openat directly into fixed fd table")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add a WARN_ON_ONCE() check to detect mm_struct instances that are
missing user_ns initialization when passed to kthread_use_mm().
When a kthread adopts an mm via kthread_use_mm(), LSM hooks and
capability checks may access current->mm->user_ns for credential
validation. If user_ns is NULL, this leads to a NULL pointer
dereference crash.
This was observed with efi_mm on arm64, where commit a5baf582f4
("arm64/efi: Call EFI runtime services without disabling preemption")
introduced kthread_use_mm(&efi_mm), but efi_mm lacked user_ns
initialization, causing crashes during /proc access.
Adding this warning helps catch similar bugs early during development
rather than waiting for hard-to-debug NULL pointer crashes in
production.
Signed-off-by: Breno Leitao <leitao@debian.org>
Acked-by: Rik van Riel <riel@surriel.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Linux 6.19-rc2 (9448598b22 ("Linux 6.19-rc2")) is crashing with a NULL
pointer dereference on arm64 hosts:
Unable to handle kernel NULL pointer dereference at virtual address 00000000000000c8
pc : cap_capable (security/commoncap.c:82 security/commoncap.c:128)
Call trace:
cap_capable (security/commoncap.c:82 security/commoncap.c:128) (P)
security_capable (security/security.c:?)
ns_capable_noaudit (kernel/capability.c:342 kernel/capability.c:381)
__ptrace_may_access (./include/linux/rcupdate.h:895 kernel/ptrace.c:326)
ptrace_may_access (kernel/ptrace.c:353)
do_task_stat (fs/proc/array.c:467)
proc_tgid_stat (fs/proc/array.c:673)
proc_single_show (fs/proc/base.c:803)
I've bissected the problem to commit a5baf582f4 ("arm64/efi: Call EFI
runtime services without disabling preemption").
>From my analyzes, the crash occurs because efi_mm lacks a user_ns field
initialization. This was previously harmless, but commit a5baf582f4
("arm64/efi: Call EFI runtime services without disabling preemption")
changed the EFI runtime call path to use kthread_use_mm(&efi_mm), which
temporarily adopts efi_mm as the current mm for the calling kthread.
When a thread has an active mm, LSM hooks like cap_capable() expect
mm->user_ns to be valid for credential checks. With efi_mm.user_ns being
NULL, capability checks during possible /proc access dereference the
NULL pointer and crash.
Fix by initializing efi_mm.user_ns to &init_user_ns.
Fixes: a5baf582f4 ("arm64/efi: Call EFI runtime services without disabling preemption")
Signed-off-by: Breno Leitao <leitao@debian.org>
Acked-by: Rik van Riel <riel@surriel.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
