drm/i915: fix integer overflow in i915_gem_execbuffer2()

On 32-bit systems, a large args->buffer_count from userspace via ioctl may overflow the allocation size, leading to out-of-bounds access. This vulnerability was introduced in commit 8408c28 ("drm/i915: First try a normal large kmalloc for the temporary exec buffers"). Signed-off-by: Xi Wang <[email protected]> Reviewed-by: Chris Wilson <[email protected]> Cc: [email protected] Signed-off-by: Daniel Vetter <[email protected]>
jbg · Apr 23, 2012 · ed8cd3b · ed8cd3b
1 parent e95c843
commit ed8cd3b
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -1404,7 +1404,8 @@ i915_gem_execbuffer2(struct drm_device *dev, void *data,
 	struct drm_i915_gem_exec_object2 *exec2_list = NULL;
 	int ret;
 
-	if (args->buffer_count < 1) {
+	if (args->buffer_count < 1 ||
+	    args->buffer_count > UINT_MAX / sizeof(*exec2_list)) {
 		DRM_DEBUG("execbuf2 with %d buffers\n", args->buffer_count);
 		return -EINVAL;
 	}