When EDID is retrieved via drm_edid_raw(), it doesn't guarantee to
return proper EDID bytes the caller wants: it may be either NULL (that
leads to an Oops) or with too long bytes over the fixed size raw_edid
array (that may lead to memory corruption). The latter was reported
actually when connected with a bad adapter.
Add sanity checks for drm_edid_raw() to address the above corner
cases, and return EDID_BAD_INPUT accordingly.
Fixes: 48edb2a4256e ("drm/amd/display: switch amdgpu_dm_connector to use struct drm_edid")
Link: https://bugzilla.suse.com/show_bug.cgi?id=1236415
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
---
BTW, I'm not sure why memmove() is used instead of memcpy().
I left as is for now.
.../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
index fbd80d8545a8..a92bc12a095e 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
@@ -980,6 +980,7 @@ enum dc_edid_status dm_helpers_read_local_edid(
enum dc_edid_status edid_status;
const struct drm_edid *drm_edid;
const struct edid *edid;
+ size_t edid_len;
if (link->aux_mode)
ddc = &aconnector->dm_dp_aux.aux.ddc;
@@ -1010,8 +1011,13 @@ enum dc_edid_status dm_helpers_read_local_edid(
return EDID_NO_RESPONSE;
edid = drm_edid_raw(drm_edid); // FIXME: Get rid of drm_edid_raw()
- sink->dc_edid.length = EDID_LENGTH * (edid->extensions + 1);
- memmove(sink->dc_edid.raw_edid, (uint8_t *)edid, sink->dc_edid.length);
+ if (!edid)
+ return EDID_BAD_INPUT;
+ edid_len = EDID_LENGTH * (edid->extensions + 1);
+ if (edid_len > sizeof(sink->dc_edid.raw_edid))
+ return EDID_BAD_INPUT;
+ sink->dc_edid.length = edid_len;
+ memmove(sink->dc_edid.raw_edid, (uint8_t *)edid, edid_len);
/* We don't need the original edid anymore */
drm_edid_free(drm_edid);
--
2.43.0
