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_bes…

Overview

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

• linux_kernel < 4.19.308
• linux_kernel >= 4.20, < 5.4.270
• linux_kernel >= 5.5, < 5.10.211
• linux_kernel >= 5.11, < 5.15.150
• linux_kernel >= 5.16, < 6.1.80
• linux_kernel >= 6.2, < 6.6.19
• linux_kernel >= 6.7, < 6.7.7
• linux_kernel = 6.8
• debian_linux = 10.0

Remediation

Upgrade past the affected range:

• linux_kernel 6.7.7