CVE-2025-40150 f2fs: fix to avoid migrating empty section
A race condition in the Linux kernel f2fs filesystem allows local attackers to trigger a filesystem shutdown, causing denial of service.
- 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-2025-40150?
CVE-2025-40150 is a 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 avoid migrating empty section
It reports a bug from device w/ zufs:
F2FS-fs (dm-64): Inconsistent segment (173822) type [1, 0] in SSA and SIT F2FS-fs (dm-64): Stopped filesystem due to reason: 4
Thread A Thread B - f2fs_expand_inode_data - f2fs_allocate_pinning_section - f2fs_gc_range - do_garbage_collect w/ segno #x - writepage - f2fs_allocate_data_block - new_curseg - allocate segno #x
The root cause is: fallocate on pinning file may race w/ block allocation as above, result in do_garbage_collect() from fallocate() may migrate segment which is just allocated by a log, the log will update segment type in its in-memory structure, however GC will get segment type from on-disk SSA block, once segment type changes by log, we can detect such inconsistency, then shutdown filesystem.
In this case, on-disk SSA shows type of segno #173822 is 1 (SUM_TYPE_NODE), however segno #173822 was just allocated as data type segment, so in-memory SIT shows type of segno #173822 is 0 (SUM_TYPE_DATA).
Change as below to fix this issue: - check whether current section is empty before gc - add sanity checks on do_garbage_collect() to avoid any race case, result in migrating segment used by log. - btw, it fixes misc issue in printed logs: "SSA and SIT" -> "SIT and SSA".
Which versions are affected by CVE-2025-40150?
How do I fix CVE-2025-40150?
Apply the vendor's patch.
Is CVE-2025-40150 being exploited?
There is no known exploitation of CVE-2025-40150 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2025-40150, DEBIAN-CVE-2025-40150, GHSA-xxcp-92h2-x7r7, ROOT-OS-DEBIAN-13-CVE-2025-40150, ROOT-OS-UBUNTU-2404-CVE-2025-40150, UBUNTU-CVE-2025-40150.