[59/74] unix: fix a race condition in unix_release()
3.2.43-rc1 review patch. If anyone has any objections, please let me know.
--
From: Paul Moore
[ 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
Signed-off-by: Paul Moore
Signed-off-by: David S. Miller
Signed-off-by: Ben Hutchings
---
net/unix/af_unix.c | 7 +++
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 317bfe3..18978b6 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -371,7 +371,7 @@ 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 dentry *dentry;
@@ -444,8 +444,6 @@ 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)
@@ -682,9 +680,10 @@ 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)
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[59/74] unix: fix a race condition in unix_release()
3.2.43-rc1 review patch. If anyone has any objections, please let me know.
--
From: Paul Moore pmo...@redhat.com
[ 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.stan...@gmail.com
Signed-off-by: Paul Moore pmo...@redhat.com
Signed-off-by: David S. Miller da...@davemloft.net
Signed-off-by: Ben Hutchings b...@decadent.org.uk
---
net/unix/af_unix.c | 7 +++
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 317bfe3..18978b6 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -371,7 +371,7 @@ 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 dentry *dentry;
@@ -444,8 +444,6 @@ 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)
@@ -682,9 +680,10 @@ 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)
--
To unsubscribe from this list: send the line unsubscribe linux-kernel in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
