CVE-2024-49960 Information

Description

In the Linux kernel the following vulnerability has been resolved:

ext4: fix timer use-after-free on failed mount

Syzbot has found an ODEBUG bug in ext4_fill_super

The del_timer_sync function cancels the s_err_report timer which reminds about filesystem errors daily. We should guarantee the timer is no longer active before kfree(sbi).

When filesystem mounting fails the flow goes to failed_mount3 where an error occurs when ext4_stop_mmpd is called causing a read I/O failure. This triggers the ext4_handle_error function that ultimately re-arms the timer leaving the s_err_report timer active before kfree(sbi) is called.

Fix the issue by canceling the s_err_report timer after calling ext4_stop_mmpd.

CVSS Vector

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

Reference

https://git.kernel.org/stable/c/9203817ba46ebba7c865c8de2aba399537b6e891 https://git.kernel.org/stable/c/fa78fb51d396f4f2f80f8e96a3b1516f394258be https://git.kernel.org/stable/c/b85569585d0154d4db1e4f9e3e6a4731d407feb0 https://git.kernel.org/stable/c/0ce160c5bdb67081a62293028dc85758a8efb22a

Attack Complexity

LOW

Privileges Required

LOW

User Interaction Required

LOW

Scope

NONE

Confidentiality Impact

UNCHANGED

Integrity Impact

HIGH

Availability Impact

HIGH

Base Score

HIGH

Base Severity

7.8