parse_edid_displayid_vrr() searches the EDID extension blocks for a
DisplayID extension before parsing the dynamic video timing range.
The code previously checked whether edid_ext was NULL after the search
loop. However, edid_ext is assigned during each iteration of the loop,
so it will never be NULL once the loop has executed. If no DisplayID
extension is found, edid_ext ends up pointing to the last extension
block, and the NULL check does not correctly detect the failure case.
Instead, check whether the loop completed without finding a matching
DisplayID block by testing "i == edid->extensions". This ensures the
function exits early when no DisplayID extension is present and avoids
parsing an unrelated EDID extension block.
Also simplify the EDID validation check using "!edid ||
!edid->extensions".
Fixes the below:
drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c:13079
parse_edid_displayid_vrr() warn: variable dereferenced before check 'edid_ext'
(see line 13075)
Fixes: a638b837d0e6 ("drm/amd/display: Fix refresh rate range for some panel")
Cc: Roman Li <[email protected]>
Cc: Alex Hung <[email protected]>
Cc: Jerry Zuo <[email protected]>
Cc: Sun peng Li <[email protected]>
Cc: Tom Chung <[email protected]>
Cc: Dan Carpenter <[email protected]>
Cc: Aurabindo Pillai <[email protected]>
Signed-off-by: Srinivasan Shanmugam <[email protected]>
---
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index 5323843c718d..acdc4abbdddc 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -13124,7 +13124,7 @@ static void parse_edid_displayid_vrr(struct
drm_connector *connector,
u16 min_vfreq;
u16 max_vfreq;
- if (edid == NULL || edid->extensions == 0)
+ if (!edid || !edid->extensions)
return;
/* Find DisplayID extension */
@@ -13134,7 +13134,7 @@ static void parse_edid_displayid_vrr(struct
drm_connector *connector,
break;
}
- if (edid_ext == NULL)
+ if (i == edid->extensions)
return;
while (j < EDID_LENGTH) {
--
2.34.1
