From: Ding Tianhong <dingtianhong@huawei.com>
Date: Sat, 29 Apr 2017 02:38:48 +0000 (+0800)
Subject: iov_iter: don't revert iov buffer if csum error
X-Git-Tag: v4.1.12-124.31.3~391
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=2314b9a460e7c5941373fc2f6715863c187970c4;p=users%2Fjedix%2Flinux-maple.git

iov_iter: don't revert iov buffer if csum error

commit a6a5993243550b09f620941dea741b7421fdf79c upstream.

The patch 327868212381 (make skb_copy_datagram_msg() et.al. preserve
->msg_iter on error) will revert the iov buffer if copy to iter
failed, but it didn't copy any datagram if the skb_checksum_complete
error, so no need to revert any data at this place.

v2: Sabrina notice that return -EFAULT when checksum error is not correct
    here, it would confuse the caller about the return value, so fix it.

Fixes: 327868212381 ("make skb_copy_datagram_msg() et.al. preserve->msg_iter on error")
Signed-off-by: Ding Tianhong <dingtianhong@huawei.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

UEK4: iov_iter_revert() doesn't exist until 4.9, so stash a copy of the
iov_iter for revert purposes [Junxiao Bi]

Orabug: 28960296
Signed-off-by: Todd Vierling <todd.vierling@oracle.com>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Signed-off-by: Brian Maly <brian.maly@oracle.com>
---

diff --git a/net/core/datagram.c b/net/core/datagram.c
index 617088aee21d4..4b1cc16eb51bc 100644
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -708,28 +708,32 @@ int skb_copy_and_csum_datagram_msg(struct sk_buff *skb,
 {
 	__wsum csum;
 	int chunk = skb->len - hlen;
+	struct iov_iter save_iter;
 
 	if (!chunk)
 		return 0;
 
 	if (msg_data_left(msg) < chunk) {
 		if (__skb_checksum_complete(skb))
-			goto csum_error;
+			return -EINVAL;
 		if (skb_copy_datagram_msg(skb, hlen, msg, chunk))
 			goto fault;
 	} else {
 		csum = csum_partial(skb->data, hlen, skb->csum);
+		memcpy(&save_iter, &msg->msg_iter, sizeof save_iter);
 		if (skb_copy_and_csum_datagram(skb, hlen, &msg->msg_iter,
 					       chunk, &csum))
 			goto fault;
-		if (csum_fold(csum))
-			goto csum_error;
+
+		if (csum_fold(csum)) {
+			memcpy(&msg->msg_iter, &save_iter, sizeof save_iter);
+			return -EINVAL;
+		}
+
 		if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE))
 			netdev_rx_csum_fault(skb->dev);
 	}
 	return 0;
-csum_error:
-	return -EINVAL;
 fault:
 	return -EFAULT;
 }