| Message ID | 20130325131833.10376.68379.stgit@localhost |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
From: Paul Moore <pmoore@redhat.com> Date: Mon, 25 Mar 2013 09:18:33 -0400 > 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> Applied, and queued up for -stable, thanks. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 51be64f..f153a8d 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -382,7 +382,7 @@ static void unix_sock_destructor(struct sock *sk) #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; @@ -451,8 +451,6 @@ static int unix_release_sock(struct sock *sk, int embrion) if (unix_tot_inflight) unix_gc(); /* Garbage collect fds */ - - return 0; } static void init_peercred(struct sock *sk) @@ -699,9 +697,10 @@ static int unix_release(struct socket *sock) 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)
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> --- net/unix/af_unix.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html