Merge branch 'fix-vsock-error-handling-regression-introduced-in-v6-17-rc1'

Will Deacon says:

====================
Fix vsock error-handling regression introduced in v6.17-rc1

Here are a couple of patches fixing the vsock error-handling regression
found by syzbot that I introduced during the recent merge window.
====================

Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: kuba-moo

include/linux/skbuff.h

@@ -4172,6 +4172,8 @@ int skb_copy_and_crc32c_datagram_iter(const struct sk_buff *skb, int offset,
 				      struct iov_iter *to, int len, u32 *crcp);
 int skb_copy_datagram_from_iter(struct sk_buff *skb, int offset,
 				 struct iov_iter *from, int len);
+int skb_copy_datagram_from_iter_full(struct sk_buff *skb, int offset,
+				     struct iov_iter *from, int len);
 int zerocopy_sg_from_iter(struct sk_buff *skb, struct iov_iter *frm);
 void skb_free_datagram(struct sock *sk, struct sk_buff *skb);
 int skb_kill_datagram(struct sock *sk, struct sk_buff *skb, unsigned int flags);

net/core/datagram.c

@@ -618,6 +618,20 @@ int skb_copy_datagram_from_iter(struct sk_buff *skb, int offset,
 }
 EXPORT_SYMBOL(skb_copy_datagram_from_iter);
 
+int skb_copy_datagram_from_iter_full(struct sk_buff *skb, int offset,
+				     struct iov_iter *from, int len)
+{
+	struct iov_iter_state state;
+	int ret;
+
+	iov_iter_save_state(from, &state);
+	ret = skb_copy_datagram_from_iter(skb, offset, from, len);
+	if (ret)
+		iov_iter_restore(from, &state);
+	return ret;
+}
+EXPORT_SYMBOL(skb_copy_datagram_from_iter_full);
+
 int zerocopy_fill_skb_from_iter(struct sk_buff *skb,
 				struct iov_iter *from, size_t length)
 {

net/vmw_vsock/virtio_transport_common.c

@@ -105,12 +105,14 @@ static int virtio_transport_fill_skb(struct sk_buff *skb,
 				     size_t len,
 				     bool zcopy)
 {
+	struct msghdr *msg = info->msg;
+
 	if (zcopy)
-		return __zerocopy_sg_from_iter(info->msg, NULL, skb,
-					       &info->msg->msg_iter, len, NULL);
+		return __zerocopy_sg_from_iter(msg, NULL, skb,
+					       &msg->msg_iter, len, NULL);
 
 	virtio_vsock_skb_put(skb, len);
-	return skb_copy_datagram_from_iter(skb, 0, &info->msg->msg_iter, len);
+	return skb_copy_datagram_from_iter_full(skb, 0, &msg->msg_iter, len);
 }
 
 static void virtio_transport_init_hdr(struct sk_buff *skb,