As reported by Jan, and others over the past few years, there is a
race condition caused by unix_release setting the sock->sk pointer
to NULL before properly marking the socket as dead/orphaned. This
can cause a problem with the LSM hook security_unix_may_send() if
there is another socket attempting to write to this partially
released socket in between when sock->sk is set to NULL and it is
marked as dead/orphaned. This patch fixes this by only setting
sock->sk to NULL after the socket has been marked as dead; I also
take the opportunity to make unix_release_sock() a void function
as it only ever returned 0/success.
Dave, I think this one should go on the -stable pile.
Special thanks to Jan for coming up with a reproducer for this
problem.
Reported-by: Jan Stancek <jan.stancek@gmail.com>
Signed-off-by: Paul Moore <pmoore@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
#endif
}
-static int unix_release_sock(struct sock *sk, int embrion)
+static void unix_release_sock(struct sock *sk, int embrion)
{
struct unix_sock *u = unix_sk(sk);
struct path path;
if (unix_tot_inflight)
unix_gc(); /* Garbage collect fds */
-
- return 0;
}
static void init_peercred(struct sock *sk)
if (!sk)
return 0;
+ unix_release_sock(sk, 0);
sock->sk = NULL;
- return unix_release_sock(sk, 0);
+ return 0;
}
static int unix_autobind(struct socket *sock)