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 0~2M 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 2~4M 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.

Classification

CVE ID: CVE-2024-50015

CVSS Base Severity: MEDIUM

CVSS Base Score: 5.5

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

Affected Products

Vendor: Linux

Product: Linux

Exploit Prediction Scoring System (EPSS)

EPSS Score: 0.04% (probability of being exploited)

EPSS Percentile: 10.17% (scored less or equal to compared to others)

EPSS Date: 2025-06-02 (when was this score calculated)

Stakeholder-Specific Vulnerability Categorization (SSVC)

SSVC Exploitation: none

SSVC Technical Impact: partial

SSVC Automatable: false

References

https://nvd.nist.gov/vuln/detail/CVE-2024-50015
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

Timeline