In the Linux kernel, the following vulnerability has been resolved:
scsi: libsas: Fix use-after-free bug in smp_execute_task_sg()
When executing SMP task failed, the smp_execute_task_sg() calls del_timer() to delete "slow_task->timer". However, if the timer handler sas_task_internal_timedout() is running, the del_timer() in smp_execute_task_sg() will not stop it and a UAF will happen. The process is shown below:
(thread 1) | (thread 2)
smp_execute_task_sg() | sas_task_internal_timedout() ... | del_timer() | ... | ... sas_free_task(task) | kfree(task->slow_task) //FREE| | task->slow_task->... //USE
Fix by calling del_timer_sync() in smp_execute_task_sg(), which makes sure the timer handler have finished before the "task->slow_task" is deallocated.
| Software | From | Fixed in |
|---|---|---|
| linux / linux_kernel | 2.6.19 | 5.4.220 |
| linux / linux_kernel | 5.5 | 5.10.150 |
| linux / linux_kernel | 5.11 | 5.15.75 |
| linux / linux_kernel | 5.16 | 5.19.17 |
| linux / linux_kernel | 6.0 | 6.0.3 |