Messages in this thread | | | Subject | Re: [PATCH] scsi: libsas: fix use-after-free bug in smp_execute_task_sg | From | Jason Yan <> | Date | Thu, 22 Sep 2022 22:06:30 +0800 |
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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@zju.edu.cn> > --- > 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@huawei.com>
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