CVE-2024-26773: ext4: avoid allocating blocks from corrupted group in ext4_mb_try_best_found()

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-04-03 · updated 2026-10-15

Description

In the Linux kernel, the following vulnerability has been resolved: ext4: avoid allocating blocks from corrupted group in ext4_mb_try_best_found() Determine if the group block bitmap is corrupted before using ac_b_ex in ext4_mb_try_best_found() to avoid allocating blocks from a group with a corrupted block bitmap in the following concurrency and making the situation worse. ext4_mb_regular_allocator ext4_lock_group(sb, group) ext4_mb_good_group // check if the group bbitmap is corrupted ext4_mb_complex_scan_group // Scan group gets ac_b_ex but doesn't use it ext4_unlock_group(sb, group) ext4_mark_group_bitmap_corrupted(group) // The block bitmap was corrupted during // the group unlock gap. ext4_mb_try_best_found ext4_lock_group(ac->ac_sb, group) ext4_mb_use_best_found mb_mark_used // Allocating blocks in block bitmap corrupted group

Affected products

Debian Linux: 10.0
Linux kernel: before 4.19.308; from 4.20 before 5.4.270; from 5.5 before 5.10.211; from 5.11 before 5.15.150; from 5.16 before 6.1.80; from 6.2 before 6.6.19 — fixed in 4.19.308, 5.10.211, 5.15.150, 5.4.270, 6.1.80, 6.6.19

How to fix

Upgrade to a fixed version: Linux kernel 4.19.308, 5.10.211, 5.15.150, 5.4.270. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2024-26773 or the next vulnerability affects your stack