Commit a6a59932 authored Apr 29, 2017 by Ding Tianhong Committed by Al Viro May 01, 2017

iov_iter: don't revert iov buffer if csum error



The patch 32786821 (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: 32786821 ("make skb_copy_datagram_msg() et.al. preserve->msg_iter on error")
Cc: stable@vger.kernel.org # v4.11
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>

parent 5ecda137

net/core/datagram.c

+7 −6

Original line number	Diff line number	Diff line
		@@ -760,7 +760,7 @@ int skb_copy_and_csum_datagram_msg(struct sk_buff *skb,

		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 {
		@@ -768,15 +768,16 @@ int skb_copy_and_csum_datagram_msg(struct sk_buff *skb,
		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)) {
		iov_iter_revert(&msg->msg_iter, chunk);
		return -EINVAL;
		}

		if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE))
		netdev_rx_csum_fault(skb->dev);
		}
		return 0;
		csum_error:
		iov_iter_revert(&msg->msg_iter, chunk);
		return -EINVAL;
		fault:
		return -EFAULT;
		}

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