| From | Greg Kroah-Hartman <> | Subject | [PATCH 3.4 184/214] drm: Pad drm_mode_get_connector to 64-bit boundary | Date | Wed, 4 Jun 2014 21:19:07 -0700 |
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3.4-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> [bwh: Backported to 3.2: adjust filename] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Cc: Weng Meiling <wengmeiling.weng@huawei.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- include/drm/drm_mode.h | 2 ++ 1 file changed, 2 insertions(+)
--- 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)
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