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

With the current screwed but its ABI, ioctls for the drm, Linus pointed out that we could allow userspace to specify the allocation size, but we pass it to the driver which then uses it blindly to store a struct. Now if userspace specifies the allocation size as smaller than the driver needs, the driver can possibly overwrite memory.

This patch restructures the driver ioctls so we store the structure size we are expecting, and make sure we allocate at least that size. The copy from/to userspace are still restricted to the size the user specifies, this allows ioctl structs to grow on both sides of the equation.

Up until now we didn't really use the DRM_IOCTL defines in the kernel, so this cleans them up and adds them for nouveau.

v2:
fix nouveau pushbuf arg (thanks to Ben for pointing it out)

Reported-by: Linus Torvalds <torvalds@linuxfoundation.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 14 insertions, 14 deletions

diff --git a/include/drm/i830_drm.h b/include/drm/i830_drm.h
index 4b00d2dd4f68..61315c29b8f3 100644
--- a/include/drm/i830_drm.h
+++ b/include/drm/i830_drm.h
@@ -264,20 +264,20 @@ typedef struct _drm_i830_sarea {
 #define DRM_I830_GETPARAM       0x0c
 #define DRM_I830_SETPARAM       0x0d
 
-#define DRM_IOCTL_I830_INIT             DRM_IOW( DRM_COMMAND_BASE + DRM_IOCTL_I830_INIT, drm_i830_init_t)
-#define DRM_IOCTL_I830_VERTEX           DRM_IOW( DRM_COMMAND_BASE + DRM_IOCTL_I830_VERTEX, drm_i830_vertex_t)
-#define DRM_IOCTL_I830_CLEAR            DRM_IOW( DRM_COMMAND_BASE + DRM_IOCTL_I830_CLEAR, drm_i830_clear_t)
-#define DRM_IOCTL_I830_FLUSH            DRM_IO ( DRM_COMMAND_BASE + DRM_IOCTL_I830_FLUSH)
-#define DRM_IOCTL_I830_GETAGE           DRM_IO ( DRM_COMMAND_BASE + DRM_IOCTL_I830_GETAGE)
-#define DRM_IOCTL_I830_GETBUF           DRM_IOWR(DRM_COMMAND_BASE + DRM_IOCTL_I830_GETBUF, drm_i830_dma_t)
-#define DRM_IOCTL_I830_SWAP             DRM_IO ( DRM_COMMAND_BASE + DRM_IOCTL_I830_SWAP)
-#define DRM_IOCTL_I830_COPY             DRM_IOW( DRM_COMMAND_BASE + DRM_IOCTL_I830_COPY, drm_i830_copy_t)
-#define DRM_IOCTL_I830_DOCOPY           DRM_IO ( DRM_COMMAND_BASE + DRM_IOCTL_I830_DOCOPY)
-#define DRM_IOCTL_I830_FLIP             DRM_IO ( DRM_COMMAND_BASE + DRM_IOCTL_I830_FLIP)
-#define DRM_IOCTL_I830_IRQ_EMIT         DRM_IOWR(DRM_COMMAND_BASE + DRM_IOCTL_I830_IRQ_EMIT, drm_i830_irq_emit_t)
-#define DRM_IOCTL_I830_IRQ_WAIT         DRM_IOW( DRM_COMMAND_BASE + DRM_IOCTL_I830_IRQ_WAIT, drm_i830_irq_wait_t)
-#define DRM_IOCTL_I830_GETPARAM         DRM_IOWR(DRM_COMMAND_BASE + DRM_IOCTL_I830_GETPARAM, drm_i830_getparam_t)
-#define DRM_IOCTL_I830_SETPARAM         DRM_IOWR(DRM_COMMAND_BASE + DRM_IOCTL_I830_SETPARAM, drm_i830_setparam_t)
+#define DRM_IOCTL_I830_INIT             DRM_IOW( DRM_COMMAND_BASE + DRM_I830_INIT, drm_i830_init_t)
+#define DRM_IOCTL_I830_VERTEX           DRM_IOW( DRM_COMMAND_BASE + DRM_I830_VERTEX, drm_i830_vertex_t)
+#define DRM_IOCTL_I830_CLEAR            DRM_IOW( DRM_COMMAND_BASE + DRM_I830_CLEAR, drm_i830_clear_t)
+#define DRM_IOCTL_I830_FLUSH            DRM_IO ( DRM_COMMAND_BASE + DRM_I830_FLUSH)
+#define DRM_IOCTL_I830_GETAGE           DRM_IO ( DRM_COMMAND_BASE + DRM_I830_GETAGE)
+#define DRM_IOCTL_I830_GETBUF           DRM_IOWR(DRM_COMMAND_BASE + DRM_I830_GETBUF, drm_i830_dma_t)
+#define DRM_IOCTL_I830_SWAP             DRM_IO ( DRM_COMMAND_BASE + DRM_I830_SWAP)
+#define DRM_IOCTL_I830_COPY             DRM_IOW( DRM_COMMAND_BASE + DRM_I830_COPY, drm_i830_copy_t)
+#define DRM_IOCTL_I830_DOCOPY           DRM_IO ( DRM_COMMAND_BASE + DRM_I830_DOCOPY)
+#define DRM_IOCTL_I830_FLIP             DRM_IO ( DRM_COMMAND_BASE + DRM_I830_FLIP)
+#define DRM_IOCTL_I830_IRQ_EMIT         DRM_IOWR(DRM_COMMAND_BASE + DRM_I830_IRQ_EMIT, drm_i830_irq_emit_t)
+#define DRM_IOCTL_I830_IRQ_WAIT         DRM_IOW( DRM_COMMAND_BASE + DRM_I830_IRQ_WAIT, drm_i830_irq_wait_t)
+#define DRM_IOCTL_I830_GETPARAM         DRM_IOWR(DRM_COMMAND_BASE + DRM_I830_GETPARAM, drm_i830_getparam_t)
+#define DRM_IOCTL_I830_SETPARAM         DRM_IOWR(DRM_COMMAND_BASE + DRM_I830_SETPARAM, drm_i830_setparam_t)
 
 typedef struct _drm_i830_clear {
         int clear_color;