linux-kernel - [PATCH] drm/amd/display: fix a possible NULL pointer dereference in bios_parser_get_src

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Date:   Mon, 19 Oct 2020 18:10:13 +0800
From:   Defang Bo <bodefang@....com>
To:     linux-kernel@...r.kernel.org
Cc:     estherbdf <603571786@...com>
Subject: [PATCH] drm/amd/display: fix a possible NULL pointer dereference in bios_parser_get_src_obj()

From: estherbdf <603571786@...com>

[Why] the func  bios_parser_get_src_obj () is similar to  bios_parser_get_dst_obj () which is fixed by the commit<a8f976473196>("drm/amd/display: Banch of smatch error and warning fixes in DC").
the symbol 'id' is uninitialized and it is not checked before dereference it,may lead to null pointer dereference.
[How] Initialized variable explicitly with NULL and add sanitizer.

Signed-off-by: estherbdf <603571786@...com>
---
 drivers/gpu/drm/amd/display/dc/bios/bios_parser.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/bios/bios_parser.c b/drivers/gpu/drm/amd/display/dc/bios/bios_parser.c
index 008d4d1..94c6cca 100644
--- a/drivers/gpu/drm/amd/display/dc/bios/bios_parser.c
+++ b/drivers/gpu/drm/amd/display/dc/bios/bios_parser.c
@@ -190,7 +190,7 @@ static enum bp_result bios_parser_get_src_obj(struct dc_bios *dcb,
 	struct graphics_object_id *src_object_id)
 {
 	uint32_t number;
-	uint16_t *id;
+	uint16_t *id = NULL;
 	ATOM_OBJECT *object;
 	struct bios_parser *bp = BP_FROM_DCB(dcb);
 
@@ -206,7 +206,7 @@ static enum bp_result bios_parser_get_src_obj(struct dc_bios *dcb,
 
 	number = get_src_obj_list(bp, object, &id);
 
-	if (number <= index)
+	if (number <= index || !id)
 		return BP_RESULT_BADINPUT;
 
 	*src_object_id = object_id_from_bios_object_id(id[index]);
-- 
1.9.1