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

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From: Chris Wilson chris@chris-wilson.co.uk

commit bc5bd37ce48c66e9192ad2e7231e9678880f6f8e upstream.

Pavel Roskin reported that DRM_IOCTL_MODE_GETCONNECTOR was overwritting the 4 bytes beyond the end of its structure with a 32-bit userspace running on a 64-bit kernel. This is due to the padding gcc inserts as the drm_mode_get_connector struct includes a u64 and its size is not a natural multiple of u64s.

64-bit kernel:

sizeof(drm_mode_get_connector)=80, alignof=8 sizeof(drm_mode_get_encoder)=20, alignof=4 sizeof(drm_mode_modeinfo)=68, alignof=4

32-bit userspace:

sizeof(drm_mode_get_connector)=76, alignof=4 sizeof(drm_mode_get_encoder)=20, alignof=4 sizeof(drm_mode_modeinfo)=68, alignof=4

Fortuituously we can insert explicit padding to the tail of our structures without breaking ABI.

Reported-by: Pavel Roskin proski@gnu.org Signed-off-by: Chris Wilson chris@chris-wilson.co.uk Cc: Dave Airlie airlied@redhat.com Cc: dri-devel@lists.freedesktop.org Signed-off-by: Dave Airlie airlied@redhat.com [ luis: backported to 3.5: - file rename: include/uapi/drm/drm_mode.h -> include/drm/drm_mode.h ] Signed-off-by: Luis Henriques luis.henriques@canonical.com --- include/drm/drm_mode.h | 2 ++ 1 file changed, 2 insertions(+)

diff --git a/include/drm/drm_mode.h b/include/drm/drm_mode.h index 3d6301b..f604a1a 100644 --- a/include/drm/drm_mode.h +++ b/include/drm/drm_mode.h @@ -223,6 +223,8 @@ struct drm_mode_get_connector { __u32 connection; __u32 mm_width, mm_height; /**< HxW in millimeters */ __u32 subpixel; + + __u32 pad; };

#define DRM_MODE_PROP_PENDING (1<<0)