CVE-2025-68264 ext4: refresh inline data size before write operations
A race condition in the Linux kernel ext4 filesystem allows local attackers to trigger a kernel crash via concurrent inline data and xattr operations.
- 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-2025-68264?
CVE-2025-68264 is a vulnerability in Linux, published on 16 Dec 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:
ext4: refresh inline data size before write operations
The cached ei->i_inline_size can become stale between the initial size check and when ext4_update_inline_data()/ext4_create_inline_data() use it. Although ext4_get_max_inline_size() reads the correct value at the time of the check, concurrent xattr operations can modify i_inline_size before ext4_write_lock_xattr() is acquired.
This causes ext4_update_inline_data() and ext4_create_inline_data() to work with stale capacity values, leading to a BUG_ON() crash in ext4_write_inline_data():
kernel BUG at fs/ext4/inline.c:1331! BUG_ON(pos + len > EXT4_I(inode)->i_inline_size);
The race window: 1. ext4_get_max_inline_size() reads i_inline_size = 60 (correct) 2. Size check passes for 50-byte write 3. [Another thread adds xattr, i_inline_size changes to 40] 4. ext4_write_lock_xattr() acquires lock 5. ext4_update_inline_data() uses stale i_inline_size = 60 6. Attempts to write 50 bytes but only 40 bytes actually available 7. BUG_ON() triggers
Fix this by recalculating i_inline_size via ext4_find_inline_data_nolock() immediately after acquiring xattr_sem. This ensures ext4_update_inline_data() and ext4_create_inline_data() work with current values that are protected from concurrent modifications.
This is similar to commit a54c4613dac1 ("ext4: fix race writing to an inline_data file while its xattrs are changing") which fixed i_inline_off staleness. This patch addresses the related i_inline_size staleness issue.
Which versions are affected by CVE-2025-68264?
How do I fix CVE-2025-68264?
Apply the vendor's patch.
Is CVE-2025-68264 being exploited?
There is no known exploitation of CVE-2025-68264 in the wild and no public exploit code.
Sources
Also known as AZL-72455, BELL-CVE-2025-68264, DEBIAN-CVE-2025-68264, GHSA-wp53-jh6w-3pf7, ROOT-OS-DEBIAN-11-CVE-2025-68264, ROOT-OS-DEBIAN-12-CVE-2025-68264 and 3 more.