The following commit has been merged into the perf/urgent branch of tip: Commit-ID: b89a05b21f46150ac10a962aa50109250b56b03b Gitweb: https://git.kernel.org/tip/b89a05b21f46150ac10a962aa50109250b56b03b Author: Baptiste Lepers <baptiste.lepers@xxxxxxxxx> AuthorDate: Mon, 06 Sep 2021 11:53:10 +10:00 Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx> CommitterDate: Wed, 15 Sep 2021 17:49:06 +02:00 events: Reuse value read using READ_ONCE instead of re-reading it In perf_event_addr_filters_apply, the task associated with the event (event->ctx->task) is read using READ_ONCE at the beginning of the function, checked, and then re-read from event->ctx->task, voiding all guarantees of the checks. Reuse the value that was read by READ_ONCE to ensure the consistency of the task struct throughout the function. Fixes: 375637bc52495 ("perf/core: Introduce address range filtering") Signed-off-by: Baptiste Lepers <baptiste.lepers@xxxxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Link: https://lkml.kernel.org/r/20210906015310.12802-1-baptiste.lepers@xxxxxxxxx --- kernel/events/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 744e872..0c000cb 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -10193,7 +10193,7 @@ static void perf_event_addr_filters_apply(struct perf_event *event) return; if (ifh->nr_file_filters) { - mm = get_task_mm(event->ctx->task); + mm = get_task_mm(task); if (!mm) goto restart;
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