net/smc: fix TCP fallback socket release

[ Upstream commit 78abe3d0dfad196959b1246003366e2610775ea6 ]

clcsock can be released while kernel_accept() references it in TCP
listen worker. Also, clcsock needs to wake up before released if TCP
fallback is used and the clcsock is blocked by accept. Add a lock to
safely release clcsock and call kernel_sock_shutdown() to wake up
clcsock from accept in smc_release().

Reported-by: syzbot+0bf2e01269f1274b4b03@syzkaller.appspotmail.com
Reported-by: syzbot+e3132895630f957306bc@syzkaller.appspotmail.com
Signed-off-by: Myungho Jung <mhjungk@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index 80e2119..2b8f952 100644 (file)
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -145,8 +145,14 @@ static int smc_release(struct socket *sock)
                sk->sk_shutdown |= SHUTDOWN_MASK;
        }
        if (smc->clcsock) {
+               if (smc->use_fallback && sk->sk_state == SMC_LISTEN) {
+                       /* wake up clcsock accept */
+                       rc = kernel_sock_shutdown(smc->clcsock, SHUT_RDWR);
+               }
+               mutex_lock(&smc->clcsock_release_lock);
                sock_release(smc->clcsock);
                smc->clcsock = NULL;
+               mutex_unlock(&smc->clcsock_release_lock);
        }
        if (smc->use_fallback) {
                if (sk->sk_state != SMC_LISTEN && sk->sk_state != SMC_INIT)
@@ -203,6 +209,7 @@ static struct sock *smc_sock_alloc(struct net *net, struct socket *sock,
        spin_lock_init(&smc->conn.send_lock);
        sk->sk_prot->hash(sk);
        sk_refcnt_debug_inc(sk);
+       mutex_init(&smc->clcsock_release_lock);
 
        return sk;
 }
@@ -818,7 +825,7 @@ static int smc_clcsock_accept(struct smc_sock *lsmc, struct smc_sock **new_smc)
        struct socket *new_clcsock = NULL;
        struct sock *lsk = &lsmc->sk;
        struct sock *new_sk;
-       int rc;
+       int rc = -EINVAL;
 
        release_sock(lsk);
        new_sk = smc_sock_alloc(sock_net(lsk), NULL, lsk->sk_protocol);
@@ -831,7 +838,10 @@ static int smc_clcsock_accept(struct smc_sock *lsmc, struct smc_sock **new_smc)
        }
        *new_smc = smc_sk(new_sk);
 
-       rc = kernel_accept(lsmc->clcsock, &new_clcsock, 0);
+       mutex_lock(&lsmc->clcsock_release_lock);
+       if (lsmc->clcsock)
+               rc = kernel_accept(lsmc->clcsock, &new_clcsock, 0);
+       mutex_unlock(&lsmc->clcsock_release_lock);
        lock_sock(lsk);
        if  (rc < 0)
                lsk->sk_err = -rc;

diff --git a/net/smc/smc.h b/net/smc/smc.h
index 08786ac..5721416 100644 (file)
--- a/net/smc/smc.h
+++ b/net/smc/smc.h
@@ -219,6 +219,10 @@ struct smc_sock {                          /* smc sock container */
                                                 * started, waiting for unsent
                                                 * data to be sent
                                                 */
+       struct mutex            clcsock_release_lock;
+                                               /* protects clcsock of a listen
+                                                * socket
+                                                * */
 };
 
 static inline struct smc_sock *smc_sk(const struct sock *sk)