Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

Per-next-PR merge.

net/smc/af_smc.c
  b5dd4d698171 ("net/smc: llc_conf_mutex refactor, replace it with rw_semaphore")
  e40b801b3603 ("net/smc: fix potential panic dues to unprotected smc_llc_srv_add_link()")
https://lore.kernel.org/all/20230221124008.6303c330@canb.auug.org.au/

Signed-off-by: Jakub Kicinski <kuba@kernel.org>

3 files changed, 77 insertions, 67 deletions

diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c
index db2e584c625e..f011af6601c9 100644
--- a/net/l2tp/l2tp_ppp.c
+++ b/net/l2tp/l2tp_ppp.c
@@ -650,54 +650,22 @@ static int pppol2tp_tunnel_mtu(const struct l2tp_tunnel *tunnel)
 	return mtu - PPPOL2TP_HEADER_OVERHEAD;
 }
 
-/* connect() handler. Attach a PPPoX socket to a tunnel UDP socket
- */
-static int pppol2tp_connect(struct socket *sock, struct sockaddr *uservaddr,
-			    int sockaddr_len, int flags)
+static struct l2tp_tunnel *pppol2tp_tunnel_get(struct net *net,
+					       const struct l2tp_connect_info *info,
+					       bool *new_tunnel)
 {
-	struct sock *sk = sock->sk;
-	struct pppox_sock *po = pppox_sk(sk);
-	struct l2tp_session *session = NULL;
-	struct l2tp_connect_info info;
 	struct l2tp_tunnel *tunnel;
-	struct pppol2tp_session *ps;
-	struct l2tp_session_cfg cfg = { 0, };
-	bool drop_refcnt = false;
-	bool drop_tunnel = false;
-	bool new_session = false;
-	bool new_tunnel = false;
 	int error;
 
-	error = pppol2tp_sockaddr_get_info(uservaddr, sockaddr_len, &info);
-	if (error < 0)
-		return error;
+	*new_tunnel = false;
 
-	lock_sock(sk);
-
-	/* Check for already bound sockets */
-	error = -EBUSY;
-	if (sk->sk_state & PPPOX_CONNECTED)
-		goto end;
-
-	/* We don't supporting rebinding anyway */
-	error = -EALREADY;
-	if (sk->sk_user_data)
-		goto end; /* socket is already attached */
-
-	/* Don't bind if tunnel_id is 0 */
-	error = -EINVAL;
-	if (!info.tunnel_id)
-		goto end;
-
-	tunnel = l2tp_tunnel_get(sock_net(sk), info.tunnel_id);
-	if (tunnel)
-		drop_tunnel = true;
+	tunnel = l2tp_tunnel_get(net, info->tunnel_id);
 
 	/* Special case: create tunnel context if session_id and
 	 * peer_session_id is 0. Otherwise look up tunnel using supplied
 	 * tunnel id.
 	 */
-	if (!info.session_id && !info.peer_session_id) {
+	if (!info->session_id && !info->peer_session_id) {
 		if (!tunnel) {
 			struct l2tp_tunnel_cfg tcfg = {
 				.encap = L2TP_ENCAPTYPE_UDP,
@@ -706,40 +674,82 @@ static int pppol2tp_connect(struct socket *sock, struct sockaddr *uservaddr,
 			/* Prevent l2tp_tunnel_register() from trying to set up
 			 * a kernel socket.
 			 */
-			if (info.fd < 0) {
-				error = -EBADF;
-				goto end;
-			}
+			if (info->fd < 0)
+				return ERR_PTR(-EBADF);
 
-			error = l2tp_tunnel_create(info.fd,
-						   info.version,
-						   info.tunnel_id,
-						   info.peer_tunnel_id, &tcfg,
+			error = l2tp_tunnel_create(info->fd,
+						   info->version,
+						   info->tunnel_id,
+						   info->peer_tunnel_id, &tcfg,
 						   &tunnel);
 			if (error < 0)
-				goto end;
+				return ERR_PTR(error);
 
 			l2tp_tunnel_inc_refcount(tunnel);
-			error = l2tp_tunnel_register(tunnel, sock_net(sk),
-						     &tcfg);
+			error = l2tp_tunnel_register(tunnel, net, &tcfg);
 			if (error < 0) {
 				kfree(tunnel);
-				goto end;
+				return ERR_PTR(error);
 			}
-			drop_tunnel = true;
-			new_tunnel = true;
+
+			*new_tunnel = true;
 		}
 	} else {
 		/* Error if we can't find the tunnel */
-		error = -ENOENT;
 		if (!tunnel)
-			goto end;
+			return ERR_PTR(-ENOENT);
 
 		/* Error if socket is not prepped */
-		if (!tunnel->sock)
-			goto end;
+		if (!tunnel->sock) {
+			l2tp_tunnel_dec_refcount(tunnel);
+			return ERR_PTR(-ENOENT);
+		}
 	}
 
+	return tunnel;
+}
+
+/* connect() handler. Attach a PPPoX socket to a tunnel UDP socket
+ */
+static int pppol2tp_connect(struct socket *sock, struct sockaddr *uservaddr,
+			    int sockaddr_len, int flags)
+{
+	struct sock *sk = sock->sk;
+	struct pppox_sock *po = pppox_sk(sk);
+	struct l2tp_session *session = NULL;
+	struct l2tp_connect_info info;
+	struct l2tp_tunnel *tunnel;
+	struct pppol2tp_session *ps;
+	struct l2tp_session_cfg cfg = { 0, };
+	bool drop_refcnt = false;
+	bool new_session = false;
+	bool new_tunnel = false;
+	int error;
+
+	error = pppol2tp_sockaddr_get_info(uservaddr, sockaddr_len, &info);
+	if (error < 0)
+		return error;
+
+	/* Don't bind if tunnel_id is 0 */
+	if (!info.tunnel_id)
+		return -EINVAL;
+
+	tunnel = pppol2tp_tunnel_get(sock_net(sk), &info, &new_tunnel);
+	if (IS_ERR(tunnel))
+		return PTR_ERR(tunnel);
+
+	lock_sock(sk);
+
+	/* Check for already bound sockets */
+	error = -EBUSY;
+	if (sk->sk_state & PPPOX_CONNECTED)
+		goto end;
+
+	/* We don't supporting rebinding anyway */
+	error = -EALREADY;
+	if (sk->sk_user_data)
+		goto end; /* socket is already attached */
+
 	if (tunnel->peer_tunnel_id == 0)
 		tunnel->peer_tunnel_id = info.peer_tunnel_id;
 
@@ -840,8 +850,7 @@ end:
 	}
 	if (drop_refcnt)
 		l2tp_session_dec_refcount(session);
-	if (drop_tunnel)
-		l2tp_tunnel_dec_refcount(tunnel);
+	l2tp_tunnel_dec_refcount(tunnel);
 	release_sock(sk);
 
 	return error;
diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index d7a7420e81ec..a4cccdfdc00a 100644
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -1839,8 +1839,10 @@ static int smcr_serv_conf_first_link(struct smc_sock *smc)
 	smc_llc_link_active(link);
 	smcr_lgr_set_type(link->lgr, SMC_LGR_SINGLE);
 
+	down_write(&link->lgr->llc_conf_mutex);
 	/* initial contact - try to establish second link */
 	smc_llc_srv_add_link(link, NULL);
+	up_write(&link->lgr->llc_conf_mutex);
 	return 0;
 }
 
diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c
index b330a1fa453e..d52060b2680c 100644
--- a/net/smc/smc_core.c
+++ b/net/smc/smc_core.c
@@ -1124,8 +1124,9 @@ static void smcr_buf_unuse(struct smc_buf_desc *buf_desc, bool is_rmb,
 
 		smc_buf_free(lgr, is_rmb, buf_desc);
 	} else {
-		buf_desc->used = 0;
-		memset(buf_desc->cpu_addr, 0, buf_desc->len);
+		/* memzero_explicit provides potential memory barrier semantics */
+		memzero_explicit(buf_desc->cpu_addr, buf_desc->len);
+		WRITE_ONCE(buf_desc->used, 0);
 	}
 }
 
@@ -1136,19 +1137,17 @@ static void smc_buf_unuse(struct smc_connection *conn,
 		if (!lgr->is_smcd && conn->sndbuf_desc->is_vm) {
 			smcr_buf_unuse(conn->sndbuf_desc, false, lgr);
 		} else {
-			conn->sndbuf_desc->used = 0;
-			memset(conn->sndbuf_desc->cpu_addr, 0,
-			       conn->sndbuf_desc->len);
+			memzero_explicit(conn->sndbuf_desc->cpu_addr, conn->sndbuf_desc->len);
+			WRITE_ONCE(conn->sndbuf_desc->used, 0);
 		}
 	}
 	if (conn->rmb_desc) {
 		if (!lgr->is_smcd) {
 			smcr_buf_unuse(conn->rmb_desc, true, lgr);
 		} else {
-			conn->rmb_desc->used = 0;
-			memset(conn->rmb_desc->cpu_addr, 0,
-			       conn->rmb_desc->len +
-			       sizeof(struct smcd_cdc_msg));
+			memzero_explicit(conn->rmb_desc->cpu_addr,
+					 conn->rmb_desc->len + sizeof(struct smcd_cdc_msg));
+			WRITE_ONCE(conn->rmb_desc->used, 0);
 		}
 	}
 }