From a2d09569f1e3c148921ffefd2e5e0298e7c51022 Mon Sep 17 00:00:00 2001 From: Baptiste Lepers Date: Mon, 6 Sep 2021 11:53:10 +1000 Subject: events: Reuse value read using READ_ONCE instead of re-reading it commit b89a05b21f46150ac10a962aa50109250b56b03b upstream. 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 Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20210906015310.12802-1-baptiste.lepers@gmail.com Signed-off-by: Greg Kroah-Hartman --- 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 1aa094c5dedb..236e7900e3fc 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -8435,7 +8435,7 @@ static void perf_event_addr_filters_apply(struct perf_event *event) if (!ifh->nr_file_filters) return; - mm = get_task_mm(event->ctx->task); + mm = get_task_mm(task); if (!mm) goto restart; -- cgit v1.2.3