fs/fcntl.c in the "aufs 3.2.x+setfl-debian" patch in the linux-image package 3.2.0-4 (kernel 3.2.81-1) in Debian wheezy mishandles F_SETFL fcntl calls on directories, which allows local users to cause a denial of service (NULL pointer dereference and system crash) via standard filesystem operations, as demonstrated by scp from an AUFS filesystem.