path: root/net/unix
diff options
authorPaul Moore <pmoore@redhat.com>2013-03-25 03:18:33 +0000
committerDavid S. Miller <davem@davemloft.net>2013-03-25 13:11:48 -0400
commitded34e0fe8fe8c2d595bfa30626654e4b87621e0 (patch)
treec32940377c5650dfd93245964e5fdfcfd93ab528 /net/unix
parent7ebe183c6d444ef5587d803b64a1f4734b18c564 (diff)
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/unix')
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)
-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)

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