Patch "drm/vc4: Fix an integer overflow in temporary allocation layout." has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

drm/vc4: Fix an integer overflow in temporary allocation layout.

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
drm-vc4-fix-an-integer-overflow-in-temporary-allocation-layout.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Eric Anholt <[email protected]>
Date: Tue, 17 Jan 2017 21:42:53 +1100
Subject: drm/vc4: Fix an integer overflow in temporary allocation layout.

From: Eric Anholt <[email protected]>

commit 0f2ff82e11c86c05d051cae32b58226392d33bbf upstream.

We copy the unvalidated ioctl arguments from the user into kernel temporary memory to run the validation from, to avoid a race where the user updates the unvalidate contents in between validating them and copying them into the validated BO.

However, in setting up the layout of the kernel side, we failed to check one of the additions (the roundup() for shader_rec_offset) against integer overflow, allowing a nearly MAX_UINT value of bin_cl_size to cause us to under-allocate the temporary space that we then copy_from_user into.

---
 drivers/gpu/drm/vc4/vc4_gem.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

@@ -594,7 +594,8 @@ vc4_get_bcl(struct drm_device *dev, stru
 					  args->shader_rec_count);
 	struct vc4_bo *bo;
 
-	if (uniforms_offset < shader_rec_offset ||
+	if (shader_rec_offset < args->bin_cl_size ||
+	    uniforms_offset < shader_rec_offset ||
 	    exec_size < uniforms_offset ||
 	    args->shader_rec_count >= (UINT_MAX /
 					  sizeof(struct vc4_shader_state)) ||

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/drm-vc4-return-einval-on-the-overflow-checks-failing.patch queue-4.9/drm-vc4-fix-memory-leak-of-the-crtc-state.patch queue-4.9/drm-vc4-fix-an-integer-overflow-in-temporary-allocation-layout.patch queue-4.9/drm-vc4-fix-a-bounds-check.patch