Merge: core-net: stable backport for 9.5 phase 2

MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/4662

JIRA: https://issues.redhat.com/browse/RHEL-46610
Tested: LNST

A bunch of stable backports from upstream, addressing critical issues in core networking

Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Approved-by: Sabrina Dubroca <sdubroca@redhat.com>
Approved-by: Davide Caratti <dcaratti@redhat.com>
Approved-by: Marcelo Ricardo Leitner <mleitner@redhat.com>
Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com>

Merged-by: Lucas Zampieri <lzampier@redhat.com>

Author: zampierilucas

net/core/datagram.c

@@ -434,15 +434,23 @@ static int __skb_datagram_iter(const struct sk_buff *skb, int offset,
 
 		end = start + skb_frag_size(frag);
 		if ((copy = end - offset) > 0) {
-			struct page *page = skb_frag_page(frag);
-			u8 *vaddr = kmap(page);
+			u32 p_off, p_len, copied;
+			struct page *p;
+			u8 *vaddr;
 
 			if (copy > len)
 				copy = len;
-			n = INDIRECT_CALL_1(cb, simple_copy_to_iter,
-					vaddr + skb_frag_off(frag) + offset - start,
-					copy, data, to);
-			kunmap(page);
+
+			n = 0;
+			skb_frag_foreach_page(frag,
+					      skb_frag_off(frag) + offset - start,
+					      copy, p, p_off, p_len, copied) {
+				vaddr = kmap_local_page(p);
+				n += INDIRECT_CALL_1(cb, simple_copy_to_iter,
+					vaddr + p_off, p_len, data, to);
+				kunmap_local(vaddr);
+			}
+
 			offset += n;
 			if (n != copy)
 				goto short_copy;

net/core/net_namespace.c

@@ -68,12 +68,15 @@ DEFINE_COOKIE(net_cookie);
 
 static struct net_generic *net_alloc_generic(void)
 {
+	unsigned int gen_ptrs = READ_ONCE(max_gen_ptrs);
+	unsigned int generic_size;
 	struct net_generic *ng;
-	unsigned int generic_size = offsetof(struct net_generic, ptr[max_gen_ptrs]);
+
+	generic_size = offsetof(struct net_generic, ptr[gen_ptrs]);
 
 	ng = kzalloc(generic_size, GFP_KERNEL);
 	if (ng)
-		ng->s.len = max_gen_ptrs;
+		ng->s.len = gen_ptrs;
 
 	return ng;
 }
@@ -669,11 +672,16 @@ EXPORT_SYMBOL_GPL(__put_net);
  * get_net_ns - increment the refcount of the network namespace
  * @ns: common namespace (net)
  *
- * Returns the net's common namespace.
+ * Returns the net's common namespace or ERR_PTR() if ref is zero.
  */
 struct ns_common *get_net_ns(struct ns_common *ns)
 {
-	return &get_net(container_of(ns, struct net, ns))->ns;
+	struct net *net;
+
+	net = maybe_get_net(container_of(ns, struct net, ns));
+	if (net)
+		return &net->ns;
+	return ERR_PTR(-EINVAL);
 }
 EXPORT_SYMBOL_GPL(get_net_ns);
 
@@ -1242,7 +1250,11 @@ static int register_pernet_operations(struct list_head *list,
 		if (error < 0)
 			return error;
 		*ops->id = error;
-		max_gen_ptrs = max(max_gen_ptrs, *ops->id + 1);
+		/* This does not require READ_ONCE as writers already hold
+		 * pernet_ops_rwsem. But WRITE_ONCE is needed to protect
+		 * net_alloc_generic.
+		 */
+		WRITE_ONCE(max_gen_ptrs, max(max_gen_ptrs, *ops->id + 1));
 	}
 	error = __register_pernet_operations(list, ops);
 	if (error) {

net/core/sock.c

@@ -3631,6 +3631,9 @@ void sk_common_release(struct sock *sk)
 
 	sk->sk_prot->unhash(sk);
 
+	if (sk->sk_socket)
+		sk->sk_socket->sk = NULL;
+
 	/*
 	 * In this point socket cannot receive new packets, but it is possible
 	 * that some packets are in flight because some CPU runs receiver and