On 2022/9/20 22:42, Duoming Zhou wrote:
When executing SMP task failed, the smp_execute_task_sg() calls del_timer() to delete the "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 the UAF bug 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. Fixes: 2908d778ab3e ("[SCSI] aic94xx: new driver") Signed-off-by: Duoming Zhou <duoming@xxxxxxxxxx> --- drivers/scsi/libsas/sas_expander.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/scsi/libsas/sas_expander.c b/drivers/scsi/libsas/sas_expander.c index fa2209080cc..5ce25183010 100644 --- a/drivers/scsi/libsas/sas_expander.c +++ b/drivers/scsi/libsas/sas_expander.c @@ -67,7 +67,7 @@ static int smp_execute_task_sg(struct domain_device *dev, res = i->dft->lldd_execute_task(task, GFP_KERNEL);if (res) {- del_timer(&task->slow_task->timer); + del_timer_sync(&task->slow_task->timer); pr_notice("executing SMP task failed:%d\n", res); break; }
The timer should be triggered 10 seconds later. I am curious why we stay this long before del_timer(). However this change looks good to me. Reviewed-by: Jason Yan <yanaijie@xxxxxxxxxx>
