High · published October 21, 2024
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guarantee the timer is no longer active before kfree(sbi).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.
| Product | Versions | Fixed in |
|---|---|---|
| debian/debian_linux | all versions | — |
| linux/linux_kernel | < 5.10.237 | 5.10.237 |
| linux/linux_kernel | ≥ 5.11, < 5.15.181 | 5.15.181 |
| linux/linux_kernel | ≥ 5.16, < 6.1.118 | 6.1.118 |
| linux/linux_kernel | ≥ 6.2, < 6.6.55 | 6.6.55 |
| linux/linux_kernel | ≥ 6.7, < 6.10.14 | 6.10.14 |
| linux/linux_kernel | ≥ 6.11, < 6.11.3 | 6.11.3 |