[PATCH AUTOSEL 5.18 52/93] drm/amd/display: Guard against ddc_pin being NULL for AUX

Sasha Levin
2022-08-11T16:00:29Z

From: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>

[ Upstream commit bc19909f19fdc8253d720d11c948935786fbfa08 ]

[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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/amd/display/dc/dce/dce_aux.c | 5 +++++
1 file changed, 5 insertions(+)

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 8e814000db62..5620a3345e4d 100644
--- a/drivers/gpu/drm/amd/display/dc/dce/dce_aux.c
+++ b/drivers/gpu/drm/amd/display/dc/dce/dce_aux.c
@@ -573,6 +573,11 @@ int dce_aux_transfer_raw(struct ddc_service *ddc,
memset(&aux_req, 0, sizeof(aux_req));
memset(&aux_rep, 0, sizeof(aux_rep));

+ 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;
--
2.35.1