drm/amd/display: Add null pointer check in link_dpms

[why]
Check that the stream exists to add link->local_sink null pointer access
protection.

Reviewed-by: Harold Sun <harold.sun@amd.com>
Reviewed-by: Ethan Cheung <ethan.cheung@amd.com>
Signed-off-by: Charlene Liu <Charlene.Liu@amd.com>
Signed-off-by: Ivan Lipski <ivan.lipski@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/display/dc/link/link_dpms.c b/drivers/gpu/drm/amd/display/dc/link/link_dpms.c
index 4ddcdc222913d078112fee35cf0138390d73091d..2a70dcdd2e477231620b43813534e36dce4d5945 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/link/link_dpms.c
+++ b/drivers/gpu/drm/amd/display/dc/link/link_dpms.c
@@ -2226,7 +2226,11 @@ static enum dc_status enable_link(
 {
        enum dc_status status = DC_ERROR_UNEXPECTED;
        struct dc_stream_state *stream = pipe_ctx->stream;
-       struct dc_link *link = stream->link;
+       struct dc_link *link = NULL;
+
+       if (stream == NULL)
+               return DC_ERROR_UNEXPECTED;
+       link = stream->link;
 
        /* There's some scenarios where driver is unloaded with display
         * still enabled. When driver is reloaded, it may cause a display