Phonet: fix potential use-after-free in pep_sock_close()

sk_common_release() might destroy our last reference to the socket.
So an extra temporary reference is needed during cleanup.

Signed-off-by: Rémi Denis-Courmont <remi.denis-courmont@nokia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 0 deletions

diff --git a/net/phonet/pep.c b/net/phonet/pep.c
index af4d38bc3b22..7b048a35ca58 100644
--- a/net/phonet/pep.c
+++ b/net/phonet/pep.c
@@ -626,6 +626,7 @@ static void pep_sock_close(struct sock *sk, long timeout)
         struct pep_sock *pn = pep_sk(sk);
         int ifindex = 0;
 
+        sock_hold(sk); /* keep a reference after sk_common_release() */
         sk_common_release(sk);
 
         lock_sock(sk);
@@ -644,6 +645,7 @@ static void pep_sock_close(struct sock *sk, long timeout)
 
         if (ifindex)
                 gprs_detach(sk);
+        sock_put(sk);
 }
 
 static int pep_wait_connreq(struct sock *sk, int noblock)