diff options
| author | Paul Moore <pmoore@redhat.com> | 2013-03-25 03:18:33 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2013-03-25 13:11:48 -0400 |
| commit | ded34e0fe8fe8c2d595bfa30626654e4b87621e0 (patch) | |
| tree | c32940377c5650dfd93245964e5fdfcfd93ab528 /net | |
| parent | 7ebe183c6d444ef5587d803b64a1f4734b18c564 (diff) | |
| download | lwn-ded34e0fe8fe8c2d595bfa30626654e4b87621e0.tar.gz lwn-ded34e0fe8fe8c2d595bfa30626654e4b87621e0.zip | |
unix: fix a race condition in unix_release()
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>
Diffstat (limited to 'net')
| -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 51be64f163ec..f153a8d6e339 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) |