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Linux kernel SMB client memory leak fixed
CVE-2026-23205
Summary
A memory leak has been fixed in the Linux kernel's SMB client. This issue occurred when using the CIFS file system to access read-only directories. Affected users should update their kernel to the latest version to prevent potential issues. No action is required if you are already running the latest kernel version.
Original title
In the Linux kernel, the following vulnerability has been resolved:
smb/client: fix memory leak in smb2_open_file()
Reproducer:
1. server: directories are exported read-only
2. client: mount...
Original description
In the Linux kernel, the following vulnerability has been resolved:
smb/client: fix memory leak in smb2_open_file()
Reproducer:
1. server: directories are exported read-only
2. client: mount -t cifs //${server_ip}/export /mnt
3. client: dd if=/dev/zero of=/mnt/file bs=512 count=1000 oflag=direct
4. client: umount /mnt
5. client: sleep 1
6. client: modprobe -r cifs
The error message is as follows:
=============================================================================
BUG cifs_small_rq (Not tainted): Objects remaining on __kmem_cache_shutdown()
-----------------------------------------------------------------------------
Object 0x00000000d47521be @offset=14336
...
WARNING: mm/slub.c:1251 at __kmem_cache_shutdown+0x34e/0x440, CPU#0: modprobe/1577
...
Call Trace:
<TASK>
kmem_cache_destroy+0x94/0x190
cifs_destroy_request_bufs+0x3e/0x50 [cifs]
cleanup_module+0x4e/0x540 [cifs]
__se_sys_delete_module+0x278/0x400
__x64_sys_delete_module+0x5f/0x70
x64_sys_call+0x2299/0x2ff0
do_syscall_64+0x89/0x350
entry_SYSCALL_64_after_hwframe+0x76/0x7e
...
kmem_cache_destroy cifs_small_rq: Slab cache still has objects when called from cifs_destroy_request_bufs+0x3e/0x50 [cifs]
WARNING: mm/slab_common.c:532 at kmem_cache_destroy+0x16b/0x190, CPU#0: modprobe/1577
smb/client: fix memory leak in smb2_open_file()
Reproducer:
1. server: directories are exported read-only
2. client: mount -t cifs //${server_ip}/export /mnt
3. client: dd if=/dev/zero of=/mnt/file bs=512 count=1000 oflag=direct
4. client: umount /mnt
5. client: sleep 1
6. client: modprobe -r cifs
The error message is as follows:
=============================================================================
BUG cifs_small_rq (Not tainted): Objects remaining on __kmem_cache_shutdown()
-----------------------------------------------------------------------------
Object 0x00000000d47521be @offset=14336
...
WARNING: mm/slub.c:1251 at __kmem_cache_shutdown+0x34e/0x440, CPU#0: modprobe/1577
...
Call Trace:
<TASK>
kmem_cache_destroy+0x94/0x190
cifs_destroy_request_bufs+0x3e/0x50 [cifs]
cleanup_module+0x4e/0x540 [cifs]
__se_sys_delete_module+0x278/0x400
__x64_sys_delete_module+0x5f/0x70
x64_sys_call+0x2299/0x2ff0
do_syscall_64+0x89/0x350
entry_SYSCALL_64_after_hwframe+0x76/0x7e
...
kmem_cache_destroy cifs_small_rq: Slab cache still has objects when called from cifs_destroy_request_bufs+0x3e/0x50 [cifs]
WARNING: mm/slab_common.c:532 at kmem_cache_destroy+0x16b/0x190, CPU#0: modprobe/1577
- https://git.kernel.org/stable/c/3a6d6b332f92990958602c1e35ce0173e2dd62e9
- https://git.kernel.org/stable/c/743f70406264348c0830f38409eb6c40a42fb2db
- https://git.kernel.org/stable/c/9ee608a64e37cea5b4b13e436c559dd0fb2ad1b5
- https://git.kernel.org/stable/c/b64e3b5d8d759dd4333992e4ba4dadf9359952c8
- https://git.kernel.org/stable/c/e3a43633023e3cacaca60d4b8972d084a2b06236
Published: 14 Feb 2026 · Updated: 11 Mar 2026 · First seen: 6 Mar 2026