This patch is the fix for CVE-2015-7799
Upstream commit 4ab42d78e37a294ac7bc56901d563c642e03c4ae
Stable 3.2.y has included this patch in v3.2.75.
https://cdn.kernel.org/pub/linux/kernel/v3.x/ChangeLog-3.2.75
Please include in this patch to stable 4.1.y.
Best regard,
Yuki Machida