This is a note to let you know that I've just added the patch titled drm/v3d: Fix null pointer dereference of pointer perfmon to the 5.15-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: drm-v3d-fix-null-pointer-dereference-of-pointer-perf.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit d529bc755665091cf094940b50626ad9ffb63105 Author: Colin Ian King <colin.king@xxxxxxxxx> Date: Sun Apr 24 19:35:12 2022 +0100 drm/v3d: Fix null pointer dereference of pointer perfmon [ Upstream commit ce7a1ecf3f9f1fccaf67295307614511d8e11b13 ] In the unlikely event that pointer perfmon is null the WARN_ON return path occurs after the pointer has already been deferenced. Fix this by only dereferencing perfmon after it has been null checked. Fixes: 26a4dc29b74a ("drm/v3d: Expose performance counters to userspace") Signed-off-by: Colin Ian King <colin.i.king@xxxxxxxxx> Reviewed-by: Juan A. Suarez <jasuarez@xxxxxxxxxx> Signed-off-by: Melissa Wen <melissa.srw@xxxxxxxxx> Link: https://patchwork.freedesktop.org/patch/msgid/20220424183512.1365683-1-colin.i.king@xxxxxxxxx Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/gpu/drm/v3d/v3d_perfmon.c b/drivers/gpu/drm/v3d/v3d_perfmon.c index 0288ef063513..f6a88abccc7d 100644 --- a/drivers/gpu/drm/v3d/v3d_perfmon.c +++ b/drivers/gpu/drm/v3d/v3d_perfmon.c @@ -25,11 +25,12 @@ void v3d_perfmon_start(struct v3d_dev *v3d, struct v3d_perfmon *perfmon) { unsigned int i; u32 mask; - u8 ncounters = perfmon->ncounters; + u8 ncounters; if (WARN_ON_ONCE(!perfmon || v3d->active_perfmon)) return; + ncounters = perfmon->ncounters; mask = GENMASK(ncounters - 1, 0); for (i = 0; i < ncounters; i++) {