drm/amd/display: Guard against ddc_pin being NULL for AUX

[Why]
In the case where we don't support DMUB aux but we have DPIA links
in the configuration we might try to message AUX using the legacy
path - where DDC pin is NULL. This causes a NULL pointer dereference.

[How]
Guard against NULL DDC pin, return a failure for aux engine acquire.

Reviewed-by: Michael Strauss <Michael.Strauss@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/display/dc/dce/dce_aux.c b/drivers/gpu/drm/amd/display/dc/dce/dce_aux.c
index 9e39cd7b203edd96c8ff5813275ed3f4826983e2..49d3145ae8fb919da70690fa3f05fedc67801fba 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/dce/dce_aux.c
+++ b/drivers/gpu/drm/amd/display/dc/dce/dce_aux.c
@@ -572,6 +572,11 @@ int dce_aux_transfer_raw(struct ddc_service *ddc,
 
        memset(&aux_req, 0, sizeof(aux_req));
 
+       if (ddc_pin == NULL) {
+               *operation_result = AUX_RET_ERROR_ENGINE_ACQUIRE;
+               return -1;
+       }
+
        aux_engine = ddc->ctx->dc->res_pool->engines[ddc_pin->pin_data->en];
        if (!acquire(aux_engine, ddc_pin)) {
                *operation_result = AUX_RET_ERROR_ENGINE_ACQUIRE;