There's no good reason to separate the access_ok() from the copy,
especially since the access_ok() size is hard-coded instead of using
sizeof(). Instead, just use copy_from_user() directly.
Fixes: cf6e7bac6357 ("drm/i915: Add support for drm syncobjs")
Cc: Jason Ekstrand <jason@xxxxxxxxxxxxxx>
Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_gem_execbuffer.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 435ed95df144..1da703213b17 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -2087,8 +2087,6 @@ get_fence_array(struct drm_i915_gem_execbuffer2 *args,
return ERR_PTR(-EINVAL);
user = u64_to_user_ptr(args->cliprects_ptr);
- if (!access_ok(VERIFY_READ, user, nfences * 2 * sizeof(u32)))
- return ERR_PTR(-EFAULT);
fences = kvmalloc_array(args->num_cliprects, sizeof(*fences),
__GFP_NOWARN | GFP_KERNEL);
@@ -2099,7 +2097,7 @@ get_fence_array(struct drm_i915_gem_execbuffer2 *args,
struct drm_i915_gem_exec_fence fence;
struct drm_syncobj *syncobj;
- if (__copy_from_user(&fence, user++, sizeof(fence))) {
+ if (copy_from_user(&fence, user++, sizeof(fence))) {
err = -EFAULT;
goto err;
}
--
2.7.4
--
Kees Cook
Pixel Security
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