From: Colin Ian King Date: Sun, 24 Apr 2022 18:35:12 +0000 (+0100) Subject: drm/v3d: Fix null pointer dereference of pointer perfmon X-Git-Tag: v5.15.73~3654 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=4be045434923e549a50846a066a04b7b6c1d6d33;p=platform%2Fkernel%2Flinux-rpi.git 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 Reviewed-by: Juan A. Suarez Signed-off-by: Melissa Wen Link: https://patchwork.freedesktop.org/patch/msgid/20220424183512.1365683-1-colin.i.king@gmail.com Signed-off-by: Sasha Levin --- diff --git a/drivers/gpu/drm/v3d/v3d_perfmon.c b/drivers/gpu/drm/v3d/v3d_perfmon.c index 0288ef0..f6a88abc 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++) {