UBUNTU: SAUCE: apparmor: fix oops in bind_mnt when dev_path lookup fails

Bind mounts can oops when devname lookup fails because the devname is
uninitialized and used in auditing the denial.

BugLink: http://bugs.launchpad.net/bugs/1660840Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Tim Gardner <tim.gardner@canonical.com>
Acked-by: Brad Figg <brad.figg@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>

security/apparmor/mount.c

@@ -335,6 +335,7 @@ static int match_mnt_path_str(struct aa_profile *profile, const struct path *mnt
 		goto audit;
 	if (IS_ERR(devname)) {
 		error = PTR_ERR(devname);
+		devname = NULL;
 		info = devinfo;
 		goto audit;
 	}