[PATCH AUTOSEL 6.1 9/9] drm/amd/display: Avoid NULL dereference of timing generator

From: Sasha Levin
Date: Sun Nov 12 2023 - 08:30:14 EST


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 38d71b5c1f2d5..556c57c390ffd 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_stream.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_stream.c
@@ -567,7 +567,7 @@ 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);
@@ -626,7 +626,7 @@ 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