[PATCH 5.10 010/108] drm/amd/display: Skip finding free audio for unknown engine_id

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

5.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Alex Hung <alex.hung@amd.com>

[ Upstream commit 1357b2165d9ad94faa4c4a20d5e2ce29c2ff29c3 ]

[WHY]
ENGINE_ID_UNKNOWN = -1 and can not be used as an array index. Plus, it
also means it is uninitialized and does not need free audio.

[HOW]
Skip and return NULL.

This fixes 2 OVERRUN issues reported by Coverity.

Reviewed-by: Rodrigo Siqueira <rodrigo.siqueira@amd.com>
Acked-by: Wayne Lin <wayne.lin@amd.com>
Signed-off-by: Alex Hung <alex.hung@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/core/dc_resource.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_resource.c b/drivers/gpu/drm/amd/display/dc/core/dc_resource.c
index f1eda1a6496d4..0a13c06eea447 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_resource.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_resource.c
@@ -1802,6 +1802,9 @@ static struct audio *find_first_free_audio(
 {
 	int i, available_audio_count;
 
+	if (id == ENGINE_ID_UNKNOWN)
+		return NULL;
+
 	available_audio_count = pool->audio_count;
 
 	for (i = 0; i < available_audio_count; i++) {
-- 
2.43.0