A flaw was found in Linux kernel ext4 filesystem. A local user can cause an out-of-bound access in ext4getgroupinfo function and so a denial of service and a system crash by mounting and operating on a crafted ext4 filesystem image.

References:

https://bugzilla.kernel.org/showbug.cgi?id=200015

http://patchwork.ozlabs.org/patch/929792/

An upstream patch:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=6e8ab72a812396996035a37e5ca4b3b99b5d214b