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 5.14-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-r.patch
and it can be found in the queue-5.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 1902cb9ce5b79abbc5e5848446f4b19c1ee5e90a
Author: Baptiste Lepers <baptiste.lepers@xxxxxxxxx>
Date: Mon Sep 6 11:53:10 2021 +1000
events: Reuse value read using READ_ONCE instead of re-reading it
[ Upstream commit b89a05b21f46150ac10a962aa50109250b56b03b ]
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: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 1cb1f9b8392e..e5c4aca620c5 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -10192,7 +10192,7 @@ 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;
