[ 112/167] [PATCH] drm/i915: fix integer overflow in i915_gem_do_execbuffer()

Ben Hutchings
2012-05-09T06:01:25Z

From: Xi Wang <xi.wang@gmail.com>

commit 44afb3a04391a74309d16180d1e4f8386fdfa745 upstream.

On 32-bit systems, a large args->num_cliprects from userspace via ioctl
may overflow the allocation size, leading to out-of-bounds access.

This vulnerability was introduced in commit 432e58ed ("drm/i915: Avoid
allocation for execbuffer object list").

Signed-off-by: Xi Wang <xi.wang@gmail.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/gpu/drm/i915/i915_gem_execbuffer.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 7c50e58..de43194 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -1133,6 +1133,11 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data,
return -EINVAL;
}

+ if (args->num_cliprects > UINT_MAX / sizeof(*cliprects)) {
+ DRM_DEBUG("execbuf with %u cliprects\n",
+ args->num_cliprects);
+ return -EINVAL;
+ }
cliprects = kmalloc(args->num_cliprects * sizeof(*cliprects),
GFP_KERNEL);
if (cliprects == NULL) {
--
1.7.10