A possible inconsistent update of refcount was identified in `smb2_compound_op`.
Such inconsistent update could lead to possible resource leaks.
Why it is a possible bug:
1. In the comment section of the function, it clearly states that the
reference to `cfile` should be dropped after calling this function.
2. Every control flow path would check and drop the reference to
`cfile`, except the patched one.
3. Existing callers would not handle refcount update of `cfile` if
-ENOMEM is returned.
To fix the bug, an extra goto label "out" is added, to make sure that the
cleanup logic would always be respected. As the problem is caused by the
allocation failure of `vars`, the cleanup logic between label "finished"
and "out" can be safely ignored. According to the definition of function
`is_replayable_error`, the error code of "-ENOMEM" is not recoverable.
Therefore, the replay logic also gets ignored.
Signed-off-by: Shuhao Fu <sfual@cse.ust.hk>
Acked-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
Cc: stable@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>
We were returning -EOPNOTSUPP for various remap_file_range cases
but for some of these the copy_file_range_syscall() requires -EINVAL
to be returned (e.g. where source and target file ranges overlap when
source and target are the same file). This fixes xfstest generic/157
which was expecting EINVAL for that (and also e.g. for when the src
offset is beyond end of file).
Cc: stable@vger.kernel.org
Acked-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Pull smb client fix from Steve French:
"Fix for netfs smb3 oops"
* tag '6.17-rc2-smb3-client-fix' of git://git.samba.org/sfrench/cifs-2.6:
cifs: Fix oops due to uninitialised variable
Fix smb3_init_transform_rq() to initialise buffer to NULL before calling
netfs_alloc_folioq_buffer() as netfs assumes it can append to the buffer it
is given. Setting it to NULL means it should start a fresh buffer, but the
value is currently undefined.
Fixes: a2906d3316 ("cifs: Switch crypto buffer to use a folio_queue rather than an xarray")
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Steve French <sfrench@samba.org>
cc: Paulo Alcantara <pc@manguebit.org>
cc: linux-cifs@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>
When ksmbd_conn_releasing(opinfo->conn) returns true,the refcount was not
decremented properly, causing a refcount leak that prevents the count from
reaching zero and the memory from being released.
Cc: stable@vger.kernel.org
Signed-off-by: Ziyan Xu <ziyan@securitygossip.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Update the connection tracking logic to handle both IPv4 and IPv6
address families.
Cc: stable@vger.kernel.org
Fixes: e6bb919397 ("ksmbd: limit repeated connections from clients with the same IP")
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Commit 34331d7bee ("smb: client: fix first command failure during
re-negotiation") addressed a race condition by updating lstrp before
entering negotiate state. However, this approach may have some unintended
side effects.
The lstrp field is documented as "when we got last response from this
server", and updating it before actually receiving a server response
could potentially affect other mechanisms that rely on this timestamp.
For example, the SMB echo detection logic also uses lstrp as a reference
point. In scenarios with frequent user operations during reconnect states,
the repeated calls to cifs_negotiate_protocol() might continuously
update lstrp, which could interfere with the echo detection timing.
Additionally, commit 266b5d02e1 ("smb: client: fix race condition in
negotiate timeout by using more precise timing") introduced a dedicated
neg_start field specifically for tracking negotiate start time. This
provides a more precise solution for the original race condition while
preserving the intended semantics of lstrp.
Since the race condition is now properly handled by the neg_start
mechanism, the lstrp update in cifs_negotiate_protocol() is no longer
necessary and can be safely removed.
Fixes: 266b5d02e1 ("smb: client: fix race condition in negotiate timeout by using more precise timing")
Cc: stable@vger.kernel.org
Acked-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
Signed-off-by: Wang Zhaolong <wangzhaolong@huaweicloud.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
This is step 4/4 of a patch series to fix mid_q_entry memory leaks
caused by race conditions in callback execution.
In compound_send_recv(), when wait_for_response() is interrupted by
signals, the code attempts to cancel pending requests by changing
their callbacks to cifs_cancelled_callback. However, there's a race
condition between signal interruption and network response processing
that causes both mid_q_entry and server buffer leaks:
```
User foreground process cifsd
cifs_readdir
open_cached_dir
cifs_send_recv
compound_send_recv
smb2_setup_request
smb2_mid_entry_alloc
smb2_get_mid_entry
smb2_mid_entry_alloc
mempool_alloc // alloc mid
kref_init(&temp->refcount); // refcount = 1
mid[0]->callback = cifs_compound_callback;
mid[1]->callback = cifs_compound_last_callback;
smb_send_rqst
rc = wait_for_response
wait_event_state TASK_KILLABLE
cifs_demultiplex_thread
allocate_buffers
server->bigbuf = cifs_buf_get()
standard_receive3
->find_mid()
smb2_find_mid
__smb2_find_mid
kref_get(&mid->refcount) // +1
cifs_handle_standard
handle_mid
/* bigbuf will also leak */
mid->resp_buf = server->bigbuf
server->bigbuf = NULL;
dequeue_mid
/* in for loop */
mids[0]->callback
cifs_compound_callback
/* Signal interrupts wait: rc = -ERESTARTSYS */
/* if (... || midQ[i]->mid_state == MID_RESPONSE_RECEIVED) *?
midQ[0]->callback = cifs_cancelled_callback;
cancelled_mid[i] = true;
/* The change comes too late */
mid->mid_state = MID_RESPONSE_READY
release_mid // -1
/* cancelled_mid[i] == true causes mid won't be released
in compound_send_recv cleanup */
/* cifs_cancelled_callback won't executed to release mid */
```
The root cause is that there's a race between callback assignment and
execution.
Fix this by introducing per-mid locking:
- Add spinlock_t mid_lock to struct mid_q_entry
- Add mid_execute_callback() for atomic callback execution
- Use mid_lock in cancellation paths to ensure atomicity
This ensures that either the original callback or the cancellation
callback executes atomically, preventing reference count leaks when
requests are interrupted by signals.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=220404
Fixes: ee258d7915 ("CIFS: Move credit processing to mid callbacks for SMB3")
Signed-off-by: Wang Zhaolong <wangzhaolong@huaweicloud.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Since 'snprintf()' returns the number of characters emitted, an
output position may be advanced with this return value rather
than using an explicit calls to 'strlen()'. Compile tested only.
Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
Signed-off-by: Steve French <stfrench@microsoft.com>
collect_sample() is used to gather samples of the data in a Write op for
analysis to try and determine if the compression algorithm is likely to
achieve anything more quickly than actually running the compression
algorithm.
However, collect_sample() assumes that the data it is going to be sampling
is stored in an ITER_XARRAY-type iterator (which it now should never be)
and doesn't actually check that it is before accessing the underlying
xarray directly.
Fix this by replacing the code with a loop that just uses the standard
iterator functions to sample every other 2KiB block, skipping the
intervening ones. It's not quite the same as the previous algorithm as it
doesn't necessarily align to the pages within an ordinary write from the
pagecache.
Note that the btrfs code from which this was derived samples the inode's
pagecache directly rather than the iterator - but that doesn't necessarily
work for network filesystems if O_DIRECT is in operation.
Fixes: 94ae8c3fee ("smb: client: compress: LZ77 code improvements cleanup")
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
cc: Enzo Matsumiya <ematsumiya@suse.de>
cc: Shyam Prasad N <sprasad@microsoft.com>
cc: Tom Talpey <tom@talpey.com>
cc: linux-cifs@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>
Besides sending the rename request to the server, the rename process
also involves closing any deferred close, waiting for outstanding I/O
to complete as well as marking all existing open handles as deleted to
prevent them from deferring closes, which increases the race window
for potential concurrent opens on the target file.
Fix this by unhashing the dentry in advance to prevent any concurrent
opens on the target.
Signed-off-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
Reviewed-by: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-cifs@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>
According to some logs reported by customers, CIFS client might end up
reporting unlinked files as existing in stat(2) due to concurrent
opens racing with unlink(2).
Besides sending the removal request to the server, the unlink process
could involve closing any deferred close as well as marking all
existing open handles as deleted to prevent them from deferring
closes, which increases the race window for potential concurrent
opens.
Fix this by unhashing the dentry in cifs_unlink() to prevent any
subsequent opens. Any open attempts, while we're still unlinking,
will block on parent's i_rwsem.
Reported-by: Jay Shin <jaeshin@redhat.com>
Signed-off-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
Reviewed-by: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-cifs@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>
Pull more smb client updates from Steve French:
"Non-smbdirect:
- Fix null ptr deref caused by delay in global spinlock
initialization
- Two fixes for native symlink creation with SMB3.1.1 POSIX
Extensions
- Fix for socket special file creation with SMB3.1.1 POSIX Exensions
- Reduce lock contention by splitting out mid_counter_lock
- move SMB1 transport code to separate file to reduce module size
when support for legacy servers is disabled
- Two cleanup patches: rename mid_lock to make it clearer what it
protects and one to convert mid flags to bool to make clearer
Smbdirect/RDMA restructuring and fixes:
- Fix for error handling in send done
- Remove unneeded empty packet queue
- Fix put_receive_buffer error path
- Two fixes to recv_done error paths
- Remove unused variable
- Improve response and recvmsg type handling
- Fix handling of incoming message type
- Two cleanup fixes for better handling smbdirect recv io
- Two cleanup fixes for socket spinlock
- Two patches that add socket reassembly struct
- Remove unused connection_status enum
- Use flag in common header for SMBDIRECT_RECV_IO_MAX_SGE
- Two cleanup patches to introduce and use smbdirect send io
- Two cleanup patches to introduce and use smbdirect send_io struct
- Fix to return error if rdma connect takes longer than 5 seconds
- Error logging improvements
- Fix redundand call to init_waitqueue_head
- Remove unneeded wait queue"
* tag 'v6.17rc-part2-SMB3-client-fixes' of git://git.samba.org/sfrench/cifs-2.6: (33 commits)
smb: client: only use a single wait_queue to monitor smbdirect connection status
smb: client: don't call init_waitqueue_head(&info->conn_wait) twice in _smbd_get_connection
smb: client: improve logging in smbd_conn_upcall()
smb: client: return an error if rdma_connect does not return within 5 seconds
smb: client: make use of smbdirect_socket.{send,recv}_io.mem.{cache,pool}
smb: smbdirect: add smbdirect_socket.{send,recv}_io.mem.{cache,pool}
smb: client: make use of struct smbdirect_send_io
smb: smbdirect: introduce struct smbdirect_send_io
smb: client: make use of SMBDIRECT_RECV_IO_MAX_SGE
smb: smbdirect: add SMBDIRECT_RECV_IO_MAX_SGE
smb: client: remove unused enum smbd_connection_status
smb: client: make use of smbdirect_socket.recv_io.reassembly.*
smb: smbdirect: introduce smbdirect_socket.recv_io.reassembly.*
smb: client: make use of smb: smbdirect_socket.recv_io.free.{list,lock}
smb: smbdirect: introduce smbdirect_socket.recv_io.free.{list,lock}
smb: client: make use of struct smbdirect_recv_io
smb: smbdirect: introduce struct smbdirect_recv_io
smb: client: make use of smbdirect_socket->recv_io.expected
smb: smbdirect: introduce smbdirect_socket.recv_io.expected
smb: client: remove unused smbd_connection->fragment_reassembly_remaining
...
Pull smb server fixes from Steve French:
- Fix limiting repeated connections from same IP
- Fix for extracting shortname when name begins with a dot
- Four smbdirect fixes:
- three fixes to the receive path: potential unmap bug, potential
resource leaks and stale connections, and also potential use
after free race
- cleanup to remove unneeded queue
* tag 'v6.17rc-part2-ksmbd-server-fixes' of git://git.samba.org/ksmbd:
smb: server: Fix extension string in ksmbd_extract_shortname()
ksmbd: limit repeated connections from clients with the same IP
smb: server: let recv_done() avoid touching data_transfer after cleanup/move
smb: server: let recv_done() consistently call put_recvmsg/smb_direct_disconnect_rdma_connection
smb: server: make sure we call ib_dma_unmap_single() only if we called ib_dma_map_single already
smb: server: remove separate empty_recvmsg_queue
In ksmbd_extract_shortname(), strscpy() is incorrectly called with the
length of the source string (excluding the NUL terminator) rather than
the size of the destination buffer. This results in "__" being copied
to 'extension' rather than "___" (two underscores instead of three).
Use the destination buffer size instead to ensure that the string "___"
(three underscores) is copied correctly.
Cc: stable@vger.kernel.org
Fixes: e2f34481b2 ("cifsd: add server-side procedures for SMB3")
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Repeated connections from clients with the same IP address may exhaust
the max connections and prevent other normal client connections.
This patch limit repeated connections from clients with the same IP.
Reported-by: tianshuo han <hantianshuo233@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
We should call put_receive_buffer() before waking up the callers.
For the internal error case of response->type being unexpected,
we now also call smbd_disconnect_rdma_connection() instead
of not waking up the callers at all.
Note that the SMBD_TRANSFER_DATA case still has problems,
which will be addressed in the next commit in order to make
it easier to review this one.
Cc: Steve French <smfrench@gmail.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: Long Li <longli@microsoft.com>
Cc: linux-cifs@vger.kernel.org
Cc: samba-technical@lists.samba.org
Fixes: f198186aa9 ("CIFS: SMBD: Establish SMB Direct connection")
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
A kernel panic can be triggered by reading /proc/fs/cifs/debug_dirs.
The crash is a null-ptr-deref inside spin_lock(), caused by the use of the
uninitialized global spinlock cifs_tcp_ses_lock.
init_cifs()
└── cifs_proc_init()
└── // User can access /proc/fs/cifs/debug_dirs here
└── cifs_debug_dirs_proc_show()
└── spin_lock(&cifs_tcp_ses_lock); // Uninitialized!
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
Mem abort info:
ESR = 0x0000000096000005
EC = 0x25: DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x05: level 1 translation fault
Data abort info:
ISV = 0, ISS = 0x00000005, ISS2 = 0x00000000
CM = 0, WnR = 0, TnD = 0, TagAccess = 0
GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
[dfff800000000000] address between user and kernel address ranges
Internal error: Oops: 0000000096000005 [#1] SMP
Modules linked in:
CPU: 3 UID: 0 PID: 16435 Comm: stress-ng-procf Not tainted 6.16.0-10385-g79f14b5d84c6 #37 PREEMPT
Hardware name: QEMU KVM Virtual Machine, BIOS 2025.02-8ubuntu1 06/11/2025
pstate: 23400005 (nzCv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
pc : do_raw_spin_lock+0x84/0x2cc
lr : _raw_spin_lock+0x24/0x34
sp : ffff8000966477e0
x29: ffff800096647860 x28: ffff800096647b88 x27: ffff0001c0c22070
x26: ffff0003eb2b60c8 x25: ffff0001c0c22018 x24: dfff800000000000
x23: ffff0000f624e000 x22: ffff0003eb2b6020 x21: ffff0000f624e768
x20: 0000000000000004 x19: 0000000000000000 x18: 0000000000000000
x17: 0000000000000000 x16: ffff8000804b9600 x15: ffff700012cc8f04
x14: 1ffff00012cc8f04 x13: 0000000000000004 x12: ffffffffffffffff
x11: 1ffff00012cc8f00 x10: ffff80008d9af0d2 x9 : f3f3f304f1f1f1f1
x8 : 0000000000000000 x7 : 7365733c203e6469 x6 : 20656572743c2023
x5 : ffff0000e0ce0044 x4 : ffff80008a4deb6e x3 : ffff8000804b9718
x2 : 0000000000000001 x1 : 0000000000000000 x0 : 0000000000000000
Call trace:
do_raw_spin_lock+0x84/0x2cc (P)
_raw_spin_lock+0x24/0x34
cifs_debug_dirs_proc_show+0x1ac/0x4c0
seq_read_iter+0x3b0/0xc28
proc_reg_read_iter+0x178/0x2a8
vfs_read+0x5f8/0x88c
ksys_read+0x120/0x210
__arm64_sys_read+0x7c/0x90
invoke_syscall+0x98/0x2b8
el0_svc_common+0x130/0x23c
do_el0_svc+0x48/0x58
el0_svc+0x40/0x140
el0t_64_sync_handler+0x84/0x12c
el0t_64_sync+0x1ac/0x1b0
Code: aa0003f3 f9000feb f2fe7e69 f8386969 (38f86908)
---[ end trace 0000000000000000 ]---
The root cause is an initialization order problem. The lock is declared
as a global variable and intended to be initialized during module startup.
However, the procfs entry that uses this lock can be accessed by userspace
before the spin_lock_init() call has run. This creates a race window where
reading the proc file will attempt to use the lock before it is
initialized, leading to the crash.
For a global lock with a static lifetime, the correct and robust approach
is to use compile-time initialization.
Fixes: 844e5c0eb1 ("smb3 client: add way to show directory leases for improved debugging")
Signed-off-by: Yunseong Kim <ysk@kzalloc.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
