af_unix: Avoid socket->sk NULL OOPS in stream connect security hooks.

unix_release() can asynchornously set socket->sk to NULL, and
it does so without holding the unix_state_lock() on "other"
during stream connects.

However, the reverse mapping, sk->sk_socket, is only transitioned
to NULL under the unix_state_lock().

Therefore make the security hooks follow the reverse mapping instead
of the forward mapping.

Reported-by: Jeremy Fitzhardinge <jeremy@goop.org>
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 7 deletions

diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 489a85a..ccb71a0 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -2408,22 +2408,22 @@ static int smack_setprocattr(struct task_struct *p, char *name,
 
 /**
  * smack_unix_stream_connect - Smack access on UDS
- * @sock: one socket
- * @other: the other socket
+ * @sock: one sock
+ * @other: the other sock
  * @newsk: unused
  *
  * Return 0 if a subject with the smack of sock could access
  * an object with the smack of other, otherwise an error code
  */
-static int smack_unix_stream_connect(struct socket *sock,
-				     struct socket *other, struct sock *newsk)
+static int smack_unix_stream_connect(struct sock *sock,
+				     struct sock *other, struct sock *newsk)
 {
-	struct inode *sp = SOCK_INODE(sock);
-	struct inode *op = SOCK_INODE(other);
+	struct inode *sp = SOCK_INODE(sock->sk_socket);
+	struct inode *op = SOCK_INODE(other->sk_socket);
 	struct smk_audit_info ad;
 
 	smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_NET);
-	smk_ad_setfield_u_net_sk(&ad, other->sk);
+	smk_ad_setfield_u_net_sk(&ad, other);
 	return smk_access(smk_of_inode(sp), smk_of_inode(op),
 				 MAY_READWRITE, &ad);
 }