[PATCH 3.11 81/94] drm: Prevent overwriting from userspace underallocating core ioctl structs

[PATCH 3.11 81/94] drm: Prevent overwriting from userspace underallocating core ioctl structs

[Greg Kroah-Hartman]

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

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

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

commit b062672e305ce071f21eb9e18b102c2a430e0999 upstream.

Apply the protections from

commit 1b2f1489633888d4a06028315dc19d65768a1c05
Author: Dave Airlie <airlied@redhat.com>
Date:   Sat Aug 14 20:20:34 2010 +1000

    drm: block userspace under allocating buffer and having drivers overwrite it (v2)

to the core ioctl structs as well, for we found one instance where there
is a 32-/64-bit size mismatch and were guilty of writing beyond the end
of the user's buffer.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Dave Airlie <airlied@redhat.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/gpu/drm/drm_drv.c |    9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -407,9 +407,16 @@ long drm_ioctl(struct file *filp,
 		cmd = ioctl->cmd_drv;
 	}
 	else if ((nr >= DRM_COMMAND_END) || (nr < DRM_COMMAND_BASE)) {
+		u32 drv_size;
+
 		ioctl = &drm_ioctls[nr];
-		cmd = ioctl->cmd;
+
+		drv_size = _IOC_SIZE(ioctl->cmd);
 		usize = asize = _IOC_SIZE(cmd);
+		if (drv_size > asize)
+			asize = drv_size;
+
+		cmd = ioctl->cmd;
 	} else
 		goto err_i1;
 

[PATCH 3.11 82/94] drm: Pad drm_mode_get_connector to 64-bit boundary

[Greg Kroah-Hartman]

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

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

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 include/uapi/drm/drm_mode.h |    2 ++
 1 file changed, 2 insertions(+)

--- a/include/uapi/drm/drm_mode.h
+++ b/include/uapi/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)