CVE-2025-71105

In the Linux kernel, the following vulnerability has been resolved:

f2fs: use global inlinexattrslab instead of per-sb slab cache

As Hong Yun reported in mailing list:

loop7: detected capacity change from 0 to 131072 ------------[ cut here ]------------ kmemcache of name 'f2fsxattrentry-7:7' already exists WARNING: CPU: 0 PID: 24426 at mm/slabcommon.c:110 kmemcachesanitycheck mm/slabcommon.c:109 [inline] WARNING: CPU: 0 PID: 24426 at mm/slab_common.c:110 __kmemcachecreateargs+0xa6/0x320 mm/slabcommon.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:kmemcachesanitycheck mm/slabcommon.c:109 [inline] RIP: 0010:__kmemcachecreateargs+0xa6/0x320 mm/slabcommon.c:307 Call Trace:  __kmemcachecreate include/linux/slab.h:353 [inline]  f2fskmemcachecreate fs/f2fs/f2fs.h:2943 [inline]  f2fsinitxattrcaches+0xa5/0xe0 fs/f2fs/xattr.c:843  f2fsfillsuper+0x1645/0x2620 fs/f2fs/super.c:4918  gettreebdevflags+0x1fb/0x260 fs/super.c:1692  vfsgettree+0x43/0x140 fs/super.c:1815  donewmount+0x201/0x550 fs/namespace.c:3808  domount fs/namespace.c:4136 [inline]  __dosysmount fs/namespace.c:4347 [inline]  __sesysmount+0x298/0x2f0 fs/namespace.c:4324  dosyscallx64 arch/x86/entry/syscall64.c:63 [inline]  dosyscall64+0x8e/0x3a0 arch/x86/entry/syscall64.c:94  entrySYSCALL64afterhwframe+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 f2fsxattrentry-7:3 and f2fsxattrentry-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 "f2fsxattrentry-7:3", and two slab caches share the same structure and cache address.

So, if we destroy f2fsxattrentry-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 "f2fsxattrentry-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 inlinexattrslab instead of per-sb slab cache for fixing.