This is a note to let you know that I've just added the patch titled events: Reuse value read using READ_ONCE instead of re-reading it to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: events-reuse-value-read-using-read_once-instead-of-re-reading-it.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From b89a05b21f46150ac10a962aa50109250b56b03b Mon Sep 17 00:00:00 2001 From: Baptiste Lepers <baptiste.lepers@xxxxxxxxx> Date: Mon, 6 Sep 2021 11:53:10 +1000 Subject: events: Reuse value read using READ_ONCE instead of re-reading it From: Baptiste Lepers <baptiste.lepers@xxxxxxxxx> 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 <baptiste.lepers@xxxxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Link: https://lkml.kernel.org/r/20210906015310.12802-1-baptiste.lepers@xxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- kernel/events/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -8115,7 +8115,7 @@ static void perf_event_addr_filters_appl if (task == TASK_TOMBSTONE) return; - mm = get_task_mm(event->ctx->task); + mm = get_task_mm(task); if (!mm) goto restart; Patches currently in stable-queue which might be from baptiste.lepers@xxxxxxxxx are queue-4.9/events-reuse-value-read-using-read_once-instead-of-re-reading-it.patch