Commit b89a05b2 authored by Baptiste Lepers's avatar Baptiste Lepers Committed by Peter Zijlstra
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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: 375637bc ("perf/core: Introduce address range filtering")
Signed-off-by: default avatarBaptiste Lepers <baptiste.lepers@gmail.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210906015310.12802-1-baptiste.lepers@gmail.com
parent 6880fa6c

kernel/events/core.c

+1 −1
Original line number Diff line number Diff line
@@ -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;