Race condition in the ioctl_file_dedupe_range function in fs/ioctl.c in the Linux kernel through 4.7 allows local users to cause a denial of service (heap-based buffer overflow) or possibly gain privileges by changing a certain count value, aka a “double fetch” vulnerability.
git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=10eec60ce79187686e052092e5383c99b4420a20
www.openwall.com/lists/oss-security/2016/07/31/6
www.securityfocus.com/bid/92259
bugzilla.redhat.com/show_bug.cgi?id=1362457
github.com/torvalds/linux/commit/10eec60ce79187686e052092e5383c99b4420a20