From: Kees Cook Date: Mon, 11 Mar 2013 21:37:35 +0000 (-0700) Subject: drm/i915: clarify reasoning for the access_ok call X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=3058753583c6a641bac188011b4d777adec916c9;p=openwrt%2Fstaging%2Fblogic.git drm/i915: clarify reasoning for the access_ok call This clarifies the comment above the access_ok check so a missing VERIFY_READ doesn't alarm anyone. v2: - rewrote comment, thanks to Chris Wilson Signed-off-by: Kees Cook Cc: Daniel Vetter [danvet: add patch history log to commit message.] Signed-off-by: Daniel Vetter --- diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c index 934396c5f048..ea963c32772d 100644 --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c @@ -747,7 +747,11 @@ validate_exec_list(struct drm_i915_gem_exec_object2 *exec, length = exec[i].relocation_count * sizeof(struct drm_i915_gem_relocation_entry); - /* we may also need to update the presumed offsets */ + /* + * We must check that the entire relocation array is safe + * to read, but since we may need to update the presumed + * offsets during execution, check for full write access. + */ if (!access_ok(VERIFY_WRITE, ptr, length)) return -EFAULT;