[PATCH 4.2 019/110] drm: crtc: integer overflow in drm_property_create_blob()

[Greg Kroah-Hartman]

4.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

commit 9ac0934bbe52290e4e4c2a58ec41cab9b6ca8c96 upstream.

The size here comes from the user via the ioctl, it is a number between
1-u32max so the addition here could overflow on 32 bit systems.

Fixes: f453ba046074 ('DRM: add mode setting support')
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Reviewed-by: Daniel Stone <daniels@xxxxxxxxxxxxx>
Signed-off-by: Dave Airlie <airlied@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/gpu/drm/drm_crtc.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -4221,7 +4221,7 @@ drm_property_create_blob(struct drm_devi
 	struct drm_property_blob *blob;
 	int ret;
 
-	if (!length)
+	if (!length || length > ULONG_MAX - sizeof(struct drm_property_blob))
 		return ERR_PTR(-EINVAL);
 
 	blob = kzalloc(sizeof(struct drm_property_blob)+length, GFP_KERNEL);


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