From dadc47f87a5b6af7cad78ceee9a19f41ef1ff3c1 Mon Sep 17 00:00:00 2001 From: Baptiste Lepers Date: Mon, 11 Oct 2021 13:28:07 +0530 Subject: [PATCH] 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") Change-Id: Ia4f6161cfc2c95073aeaff85936efa737508c5a2 Signed-off-by: Baptiste Lepers Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20210906015310.12802-1-baptiste.lepers@xxxxxxxxx Signed-off-by: Greg Kroah-Hartman Signed-off-by: Baptiste Lepers Git-repo: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git Git-commit: b89a05b21f46150ac10a962aa50109250b56b03b Signed-off-by: Kishor Krishna Bhat --- 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 a6c079269f15..d563ac5abdbf 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -9343,7 +9343,7 @@ 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;