CVE-2024-50015 Information

Description

In the Linux kernel the following vulnerability has been resolved:

ext4: dax: fix overflowing extents beyond inode size when partially writing

The dax_iomap_rw() does two things in each iteration: map written blocks and copy user data to blocks. If the process is killed by user(See signal handling in dax_iomap_iter()) the copied data will be returned and added on inode size which means that the length of written extents may exceed the inode size then fsck will fail. An example is given as:

dd if=/dev/urandom of=file bs=4M count=1 dax_iomap_rw iomap_iter // round 1 ext4_iomap_begin ext4_iomap_alloc // allocate 02M extents(written flag) dax_iomap_iter // copy 2M data iomap_iter // round 2 iomap_iter_advance iter->pos += iter->processed // iter->pos = 2M ext4_iomap_begin ext4_iomap_alloc // allocate 24M extents(written flag) dax_iomap_iter fatal_signal_pending done = iter->pos - iocb->ki_pos // done = 2M ext4_handle_inode_extension ext4_update_inode_size // inode size = 2M

fsck reports: Inode 13 i_size is 2097152 should be 4194304. Fix?

Fix the problem by truncating extents if the written length is smaller than expected.

CVSS Vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Reference

https://git.kernel.org/stable/c/f8a7c342326f6ad1dfdb30a18dd013c70f5e9669 https://git.kernel.org/stable/c/8c30a9a8610c314554997f86370140746aa35661 https://git.kernel.org/stable/c/abfaa876b948baaea4d14f21a1963789845c8b4c https://git.kernel.org/stable/c/5efccdee4a7d507a483f20f880b809cc4eaef14d https://git.kernel.org/stable/c/a9f331f51515bdb3ebc8d0963131af367ef468f6 https://git.kernel.org/stable/c/ec0dd451e236c46e4858d53e9e82bae7797a7af5 https://git.kernel.org/stable/c/dda898d7ffe85931f9cca6d702a51f33717c501e

Attack Complexity

LOW

Privileges Required

LOW

User Interaction Required

LOW

Scope

NONE

Confidentiality Impact

UNCHANGED

Integrity Impact

NONE

Availability Impact

NONE

Base Score

HIGH

Base Severity

5.5