[PATCH 3.7-rc8] drm: Fix possible EDID memory allocation oops

From: Tim Gardner
Date: Wed Dec 05 2012 - 14:00:00 EST

The result of drm_property_create_blob() is not checked for success
which could lead to a NULL pointer dereference.

I was led to this by a smatch warning:

drivers/gpu/drm/drm_crtc.c:3186 drm_mode_connector_update_edid_property() error: potential null dereference 'connector->edid_blob_ptr'. (drm_property_create_blob returns null)

drm_property_create_blob() calls kzalloc() which can return NULL.

Cc: David Airlie <airlied@xxxxxxxx>
Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx # 3.0+
Signed-off-by: Tim Gardner <tim.gardner@xxxxxxxxxxxxx>

This bug actually exists in the original commit f453ba0460742ad027ae0c4c7d61e62817b3e7ef
(2.6.29), but I only checked as far back as 3.0 for stable.

drivers/gpu/drm/drm_crtc.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index ef1b221..31872ba 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -3180,6 +3180,10 @@ int drm_mode_connector_update_edid_property(struct drm_connector *connector,
size = EDID_LENGTH * (1 + edid->extensions);
connector->edid_blob_ptr = drm_property_create_blob(connector->dev,
size, edid);
+ if (!connector->edid_blob_ptr) {
+ pr_err("drm: Could not allocate %d edid blob bytes.\n", size);
+ return -ENOMEM;
+ }

ret = drm_connector_property_set_value(connector,

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