From dc69b48988b171d6ccb3a083607e4dff015e2c0d Mon Sep 17 00:00:00 2001 From: Meenakshikumar Somasundaram Date: Mon, 29 Sep 2025 14:28:34 -0400 Subject: [PATCH] drm/amd/display: Fix NULL pointer dereference [Why] On a mst branch with multi display setup, dc context is obselete after updating the first stream. Referencing the same dc context for the next stream update to fetch dc pointer leads to NULL pointer dereference. [How] Get the dc pointer from the link rather than context. Cc: Mario Limonciello Cc: Alex Deucher Reviewed-by: Charlene Liu Signed-off-by: Meenakshikumar Somasundaram Signed-off-by: Aurabindo Pillai Signed-off-by: Alex Deucher --- drivers/gpu/drm/amd/display/dc/link/accessories/link_dp_cts.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/amd/display/dc/link/accessories/link_dp_cts.c b/drivers/gpu/drm/amd/display/dc/link/accessories/link_dp_cts.c index 1593412354cf8..1045c268672e2 100644 --- a/drivers/gpu/drm/amd/display/dc/link/accessories/link_dp_cts.c +++ b/drivers/gpu/drm/amd/display/dc/link/accessories/link_dp_cts.c @@ -78,6 +78,7 @@ static void dp_retrain_link_dp_test(struct dc_link *link, struct audio_output audio_output[MAX_PIPES]; struct dc_stream_state *streams_on_link[MAX_PIPES]; int num_streams_on_link = 0; + struct dc *dc = (struct dc *)link->dc; needs_divider_update = (link->dc->link_srv->dp_get_encoding_format(link_setting) != link->dc->link_srv->dp_get_encoding_format((const struct dc_link_settings *) &link->cur_link_settings)); @@ -150,7 +151,7 @@ static void dp_retrain_link_dp_test(struct dc_link *link, if (streams_on_link[i] && streams_on_link[i]->link && streams_on_link[i]->link == link) { stream_update.stream = streams_on_link[i]; stream_update.dpms_off = &dpms_off; - dc_update_planes_and_stream(state->clk_mgr->ctx->dc, NULL, 0, streams_on_link[i], &stream_update); + dc_update_planes_and_stream(dc, NULL, 0, streams_on_link[i], &stream_update); } } } -- 2.47.3