f2fs Slab Cache Conflict in Linux Kernel
CVE-2025-71105 Published on January 14, 2026
f2fs: use global inline_xattr_slab instead of per-sb slab cache
In the Linux kernel, the following vulnerability has been resolved:
f2fs: use global inline_xattr_slab instead of per-sb slab cache
As Hong Yun reported in mailing list:
loop7: detected capacity change from 0 to 131072
------------[ cut here ]------------
kmem_cache of name 'f2fs_xattr_entry-7:7' already exists
WARNING: CPU: 0 PID: 24426 at mm/slab_common.c:110 kmem_cache_sanity_check mm/slab_common.c:109 [inline]
WARNING: CPU: 0 PID: 24426 at mm/slab_common.c:110 __kmem_cache_create_args+0xa6/0x320 mm/slab_common.c:307
CPU: 0 UID: 0 PID: 24426 Comm: syz.7.1370 Not tainted 6.17.0-rc4 #1 PREEMPT(full)
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
RIP: 0010:kmem_cache_sanity_check mm/slab_common.c:109 [inline]
RIP: 0010:__kmem_cache_create_args+0xa6/0x320 mm/slab_common.c:307
Call Trace:
__kmem_cache_create include/linux/slab.h:353 [inline]
f2fs_kmem_cache_create fs/f2fs/f2fs.h:2943 [inline]
f2fs_init_xattr_caches+0xa5/0xe0 fs/f2fs/xattr.c:843
f2fs_fill_super+0x1645/0x2620 fs/f2fs/super.c:4918
get_tree_bdev_flags+0x1fb/0x260 fs/super.c:1692
vfs_get_tree+0x43/0x140 fs/super.c:1815
do_new_mount+0x201/0x550 fs/namespace.c:3808
do_mount fs/namespace.c:4136 [inline]
__do_sys_mount fs/namespace.c:4347 [inline]
__se_sys_mount+0x298/0x2f0 fs/namespace.c:4324
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x8e/0x3a0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x76/0x7e
The bug can be reproduced w/ below scripts:
- mount /dev/vdb /mnt1
- mount /dev/vdc /mnt2
- umount /mnt1
- mounnt /dev/vdb /mnt1
The reason is if we created two slab caches, named f2fs_xattr_entry-7:3
and f2fs_xattr_entry-7:7, and they have the same slab size. Actually,
slab system will only create one slab cache core structure which has
slab name of "f2fs_xattr_entry-7:3", and two slab caches share the same
structure and cache address.
So, if we destroy f2fs_xattr_entry-7:3 cache w/ cache address, it will
decrease reference count of slab cache, rather than release slab cache
entirely, since there is one more user has referenced the cache.
Then, if we try to create slab cache w/ name "f2fs_xattr_entry-7:3" again,
slab system will find that there is existed cache which has the same name
and trigger the warning.
Let's changes to use global inline_xattr_slab instead of per-sb slab cache
for fixing.
Products Associated with CVE-2025-71105
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Affected Versions
Linux:- Version a999150f4fe3abbb7efd05411fd5b460be699943 and below 93d30fe19660dec6bf1bd3d5c186c1c737b21aa5 is affected.
- Version a999150f4fe3abbb7efd05411fd5b460be699943 and below 474cc3ed37436ddfd63cac8dbffe3b1e219e9100 is affected.
- Version a999150f4fe3abbb7efd05411fd5b460be699943 and below 72ce19dfed162da6e430467333b2da70471d08a4 is affected.
- Version a999150f4fe3abbb7efd05411fd5b460be699943 and below be4c3a3c6c2304a8fcd14095d18d26f0cc4e222a is affected.
- Version a999150f4fe3abbb7efd05411fd5b460be699943 and below 1eb0b130196bcbc56c5c80c83139fa70c0aa82c5 is affected.
- Version a999150f4fe3abbb7efd05411fd5b460be699943 and below e6d828eae00ec192e18c2ddaa2fd32050a96048a is affected.
- Version a999150f4fe3abbb7efd05411fd5b460be699943 and below 1f27ef42bb0b7c0740c5616ec577ec188b8a1d05 is affected.
- Version 5.7 is affected.
- Before 5.7 is unaffected.
- Version 5.10.248, <= 5.10.* is unaffected.
- Version 5.15.198, <= 5.15.* is unaffected.
- Version 6.1.160, <= 6.1.* is unaffected.
- Version 6.6.120, <= 6.6.* is unaffected.
- Version 6.12.64, <= 6.12.* is unaffected.
- Version 6.18.3, <= 6.18.* is unaffected.
- Version 6.19, <= * is unaffected.
Exploit Probability
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