selinux: Fix a panic in selinux_netlbl_inode_permission()

Rick McNeal from LSI identified a panic in selinux_netlbl_inode_permission()
caused by a certain sequence of SUNRPC operations.  The problem appears to be
due to the lack of NULL pointer checking in the function; this patch adds the
pointer checks so the function will exit safely in the cases where the socket
is not completely initialized.

Signed-off-by: Paul Moore <paul.moore@hp.com>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 3 insertions, 2 deletions

diff --git a/security/selinux/netlabel.c b/security/selinux/netlabel.c
index 3f4b26647386..350794ab9b42 100644
--- a/security/selinux/netlabel.c
+++ b/security/selinux/netlabel.c
@@ -386,11 +386,12 @@ int selinux_netlbl_inode_permission(struct inode *inode, int mask)
         if (!S_ISSOCK(inode->i_mode) ||
             ((mask & (MAY_WRITE | MAY_APPEND)) == 0))
                 return 0;
-
         sock = SOCKET_I(inode);
         sk = sock->sk;
+        if (sk == NULL)
+                return 0;
         sksec = sk->sk_security;
-        if (sksec->nlbl_state != NLBL_REQUIRE)
+        if (sksec == NULL || sksec->nlbl_state != NLBL_REQUIRE)
                 return 0;
 
         local_bh_disable();