A flaw was found in Linux kernel in the ext4 filesystem code. A
use-after-free is possible in ext4_ext_remove_space() function when
mounting and operating a crafted ext4 image.

Wen Xu discovered that a use-after-free vulnerability existed in the ext4
filesystem implementation in the Linux kernel. An attacker could use this
to construct a malicious ext4 image that, when mounted, could cause a
denial of service (system crash) or possibly execute arbitrary code.

 sbeattie> fs/ext4/balloc.c
 sbeattie> first issue in bugzilla report may require additional fix
 sbeattie> possible reproducer in bug report