Messages in this thread | | | Subject | Re: [PATCH] sched/numa: Fix use-after-free bug in the task_numa_compare | From | Rik van Riel <> | Date | Mon, 18 Jan 2016 09:03:19 -0500 |
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On 01/18/2016 08:59 AM, gavin.guo@canonical.com wrote: > From: Gavin Guo <gavin.guo@canonical.com>
> As commit 1effd9f19324 ("sched/numa: Fix unsafe get_task_struct() in > task_numa_assign()") points out, the rcu_read_lock() cannot protect the > task_struct from being freed in the finish_task_switch(). And the bug > happens in the process of calculation of imp which requires the access of > p->numa_faults being freed in the following path: > > do_exit() > current->flags |= PF_EXITING; > release_task() > ~~delayed_put_task_struct()~~ > schedule() > ... > ... > rq->curr = next; > context_switch() > finish_task_switch() > put_task_struct() > __put_task_struct() > task_numa_free() > > The fix here to get_task_struct() early before end of dst_rq->lock to > protect the calculation process and also put_task_struct() in the > corresponding point if finally the dst_rq->curr somehow cannot be > assigned. > > BugLink: https://bugs.launchpad.net/bugs/1527643 > Signed-off-by: Gavin Guo <gavin.guo@canonical.com> > Signed-off-by: Liang Chen <liangchen.linux@gmail.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
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