CVE-2025-40137 f2fs: fix to truncate first page in error path of f2fs_truncate()
A local attacker can trigger a kernel bug in the F2FS filesystem driver by mounting a corrupted image, causing a system crash.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-40137?
CVE-2025-40137 is a denial of service vulnerability in Linux, published on 12 Nov 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
f2fs: fix to truncate first page in error path of f2fs_truncate()
syzbot reports a bug as below:
loop0: detected capacity change from 0 to 40427 F2FS-fs (loop0): Wrong SSA boundary, start(3584) end(4096) blocks(3072) F2FS-fs (loop0): Can't find valid F2FS filesystem in 1th superblock F2FS-fs (loop0): invalid crc value F2FS-fs (loop0): f2fs_convert_inline_folio: corrupted inline inode ino=3, i_addr[0]:0x1601, run fsck to fix. ------------[ cut here ]------------ kernel BUG at fs/inode.c:753! RIP: 0010:clear_inode+0x169/0x190 fs/inode.c:753 Call Trace: <TASK> evict+0x504/0x9c0 fs/inode.c:810 f2fs_fill_super+0x5612/0x6fa0 fs/f2fs/super.c:5047 get_tree_bdev_flags+0x40e/0x4d0 fs/super.c:1692 vfs_get_tree+0x8f/0x2b0 fs/super.c:1815 do_new_mount+0x2a2/0x9e0 fs/namespace.c:3808 do_mount fs/namespace.c:4136 [inline] __do_sys_mount fs/namespace.c:4347 [inline] __se_sys_mount+0x317/0x410 fs/namespace.c:4324 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f
During f2fs_evict_inode(), clear_inode() detects that we missed to truncate all page cache before destorying inode, that is because in below path, we will create page #0 in cache, but missed to drop it in error path, let's fix it.
- evict - f2fs_evict_inode - f2fs_truncate - f2fs_convert_inline_inode - f2fs_grab_cache_folio : create page #0 in cache - f2fs_convert_inline_folio : sanity check failed, return -EFSCORRUPTED - clear_inode detects that inode->i_data.nrpages is not zero
Which versions are affected by CVE-2025-40137?
How do I fix CVE-2025-40137?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2025-40137 being exploited?
There is no known exploitation of CVE-2025-40137 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2025-40137, DEBIAN-CVE-2025-40137, GHSA-g9j9-8gxh-gh9r, ROOT-OS-DEBIAN-11-CVE-2025-40137, ROOT-OS-DEBIAN-12-CVE-2025-40137, ROOT-OS-DEBIAN-13-CVE-2025-40137 and 3 more.