drm/amd/display: Check link_index before accessing dc->links[]

[WHY & HOW]
dc->links[] has max size of MAX_LINKS and NULL is return when trying to
access with out-of-bound index.

This fixes 3 OVERRUN and 1 RESOURCE_LEAK issues reported by Coverity.

Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Acked-by: Tom Chung <chiahsuan.chung@amd.com>
Signed-off-by: Alex Hung <alex.hung@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/core/dc_link_exports.c b/drivers/gpu/drm/amd/display/dc/core/dc_link_exports.c
index c6c3503..dfdfe22 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link_exports.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link_exports.c
@@ -37,6 +37,9 @@
 #include "dce/dce_i2c.h"
 struct dc_link *dc_get_link_at_index(struct dc *dc, uint32_t link_index)
 {
+       if (link_index >= MAX_LINKS)
+               return NULL;
+
        return dc->links[link_index];
 }