[PATCH AUTOSEL 5.10 8/8] drm/amd/display: Avoid NULL dereference of timing generator

[Sasha Levin]

From: Wayne Lin <wayne.lin@xxxxxxx>

[ Upstream commit b1904ed480cee3f9f4036ea0e36d139cb5fee2d6 ]

[Why & How]
Check whether assigned timing generator is NULL or not before
accessing its funcs to prevent NULL dereference.

Reviewed-by: Jun Lei <jun.lei@xxxxxxx>
Acked-by: Hersen Wu <hersenxs.wu@xxxxxxx>
Signed-off-by: Wayne Lin <wayne.lin@xxxxxxx>
Tested-by: Daniel Wheeler <daniel.wheeler@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/gpu/drm/amd/display/dc/core/dc_stream.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_stream.c b/drivers/gpu/drm/amd/display/dc/core/dc_stream.c
index d48fd87d3b953..8206c6edba746 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_stream.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_stream.c
@@ -534,7 +534,7 @@ uint32_t dc_stream_get_vblank_counter(const struct dc_stream_state *stream)
 	for (i = 0; i < MAX_PIPES; i++) {
 		struct timing_generator *tg = res_ctx->pipe_ctx[i].stream_res.tg;
 
-		if (res_ctx->pipe_ctx[i].stream != stream)
+		if (res_ctx->pipe_ctx[i].stream != stream || !tg)
 			continue;
 
 		return tg->funcs->get_frame_count(tg);
@@ -593,7 +593,7 @@ bool dc_stream_get_scanoutpos(const struct dc_stream_state *stream,
 	for (i = 0; i < MAX_PIPES; i++) {
 		struct timing_generator *tg = res_ctx->pipe_ctx[i].stream_res.tg;
 
-		if (res_ctx->pipe_ctx[i].stream != stream)
+		if (res_ctx->pipe_ctx[i].stream != stream || !tg)
 			continue;
 
 		tg->funcs->get_scanoutpos(tg,
-- 
2.42.0