diff options
| author | Paul Moore <pmoore@redhat.com> | 2013-03-25 03:18:33 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-04-05 09:26:17 -0700 |
| commit | 9d7a1a25337ad50e9619685550e0b016ce23ddef (patch) | |
| tree | a27addca6000e0b2c25a52bda21d7c87c790c437 | |
| parent | 3ae217a9770eb723640bc07587359a2b86d96e13 (diff) | |
unix: fix a race condition in unix_release()
[ Upstream commit ded34e0fe8fe8c2d595bfa30626654e4b87621e0 ]
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | net/unix/af_unix.c | 7 |
1 files changed, 3 insertions, 4 deletions
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 5b5c876c80e9..b45eb6553ee7 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -384,7 +384,7 @@ 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; @@ -453,8 +453,6 @@ 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) @@ -701,9 +699,10 @@ 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) |