5 files changed, 40 insertions, 10 deletions

diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index ae54f26709ca..03cf87d3b380 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -796,11 +796,19 @@ static __net_init int net_ns_net_init(struct net *net)
 #ifdef CONFIG_NET_NS
 	net->ns.ops = &netns_operations;
 #endif
+	if (net == &init_net) {
+		net->ns.inum = PROC_NET_INIT_INO;
+		return 0;
+	}
 	return ns_alloc_inum(&net->ns);
 }
 
 static __net_exit void net_ns_net_exit(struct net *net)
 {
+	/*
+	 * Initial network namespace doesn't exit so we don't need any
+	 * special checks here.
+	 */
 	ns_free_inum(&net->ns);
 }
 
diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index 4ddb7490df4b..6ad84d4a2b46 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -432,6 +432,7 @@ int netpoll_send_udp(struct netpoll *np, const char *msg, int len)
 	udph->dest = htons(np->remote_port);
 	udph->len = htons(udp_len);
 
+	udph->check = 0;
 	if (np->ipv6) {
 		udph->check = csum_ipv6_magic(&np->local_ip.in6,
 					      &np->remote_ip.in6,
@@ -460,7 +461,6 @@ int netpoll_send_udp(struct netpoll *np, const char *msg, int len)
 		skb_reset_mac_header(skb);
 		skb->protocol = eth->h_proto = htons(ETH_P_IPV6);
 	} else {
-		udph->check = 0;
 		udph->check = csum_tcpudp_magic(np->local_ip.ip,
 						np->remote_ip.ip,
 						udp_len, IPPROTO_UDP,
diff --git a/net/core/scm.c b/net/core/scm.c
index 0225bd94170f..072d5742440a 100644
--- a/net/core/scm.c
+++ b/net/core/scm.c
@@ -23,6 +23,8 @@
 #include <linux/security.h>
 #include <linux/pid_namespace.h>
 #include <linux/pid.h>
+#include <uapi/linux/pidfd.h>
+#include <linux/pidfs.h>
 #include <linux/nsproxy.h>
 #include <linux/slab.h>
 #include <linux/errqueue.h>
@@ -145,6 +147,22 @@ void __scm_destroy(struct scm_cookie *scm)
 }
 EXPORT_SYMBOL(__scm_destroy);
 
+static inline int scm_replace_pid(struct scm_cookie *scm, struct pid *pid)
+{
+	int err;
+
+	/* drop all previous references */
+	scm_destroy_cred(scm);
+
+	err = pidfs_register_pid(pid);
+	if (unlikely(err))
+		return err;
+
+	scm->pid = pid;
+	scm->creds.pid = pid_vnr(pid);
+	return 0;
+}
+
 int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *p)
 {
 	const struct proto_ops *ops = READ_ONCE(sock->ops);
@@ -189,15 +207,21 @@ int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *p)
 			if (err)
 				goto error;
 
-			p->creds.pid = creds.pid;
 			if (!p->pid || pid_vnr(p->pid) != creds.pid) {
 				struct pid *pid;
 				err = -ESRCH;
 				pid = find_get_pid(creds.pid);
 				if (!pid)
 					goto error;
-				put_pid(p->pid);
-				p->pid = pid;
+
+				/* pass a struct pid reference from
+				 * find_get_pid() to scm_replace_pid().
+				 */
+				err = scm_replace_pid(p, pid);
+				if (err) {
+					put_pid(pid);
+					goto error;
+				}
 			}
 
 			err = -EINVAL;
@@ -459,7 +483,7 @@ static void scm_pidfd_recv(struct msghdr *msg, struct scm_cookie *scm)
 	if (!scm->pid)
 		return;
 
-	pidfd = pidfd_prepare(scm->pid, 0, &pidfd_file);
+	pidfd = pidfd_prepare(scm->pid, PIDFD_STALE, &pidfd_file);
 
 	if (put_cmsg(msg, SOL_SOCKET, SCM_PIDFD, sizeof(int), &pidfd)) {
 		if (pidfd_file) {
diff --git a/net/core/selftests.c b/net/core/selftests.c
index 35f807ea9952..406faf8e5f3f 100644
--- a/net/core/selftests.c
+++ b/net/core/selftests.c
@@ -160,8 +160,9 @@ static struct sk_buff *net_test_get_skb(struct net_device *ndev,
 	skb->csum = 0;
 	skb->ip_summed = CHECKSUM_PARTIAL;
 	if (attr->tcp) {
-		thdr->check = ~tcp_v4_check(skb->len, ihdr->saddr,
-					    ihdr->daddr, 0);
+		int l4len = skb->len - skb_transport_offset(skb);
+
+		thdr->check = ~tcp_v4_check(l4len, ihdr->saddr, ihdr->daddr, 0);
 		skb->csum_start = skb_transport_header(skb) - skb->head;
 		skb->csum_offset = offsetof(struct tcphdr, check);
 	} else {
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 85fc82f72d26..d6420b74ea9c 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -6261,9 +6261,6 @@ int skb_ensure_writable(struct sk_buff *skb, unsigned int write_len)
 	if (!pskb_may_pull(skb, write_len))
 		return -ENOMEM;
 
-	if (!skb_frags_readable(skb))
-		return -EFAULT;
-
 	if (!skb_cloned(skb) || skb_clone_writable(skb, write_len))
 		return 0;