mptcp: sendmsg: reset iter on error (35759383) · Commits · 戴 / test

Once we've copied data from the iterator we need to revert in case we end up not sending any data. This bug doesn't trigger with normal 'poll' based tests, because we only feed a small chunk of data to kernel after poll indicated POLLOUT. With blocking IO and large writes this triggers. Receiver ends up with less data than it should get. Fixes: ("mptcp: avoid blocking in tcp_sendpages") Signed-off-by:

Florian Westphal <fw@strlen.de> Reviewed-by:

Mat Martineau <mathew.j.martineau@linux.intel.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

net/mptcp/protocol.c

+6 −2

Original line number	Diff line number	Diff line
		@@ -725,8 +725,10 @@ static int mptcp_sendmsg_frag(struct sock sk, struct sock ssk,
		if (!psize)
		return -EINVAL;

		if (!sk_wmem_schedule(sk, psize + dfrag->overhead))
		if (!sk_wmem_schedule(sk, psize + dfrag->overhead)) {
		iov_iter_revert(&msg->msg_iter, psize);
		return -ENOMEM;
		}
		} else {
		offset = dfrag->offset;
		psize = min_t(size_t, dfrag->data_len, avail_size);
		@@ -737,8 +739,10 @@ static int mptcp_sendmsg_frag(struct sock sk, struct sock ssk,
		*/
		ret = do_tcp_sendpages(ssk, page, offset, psize,
		msg->msg_flags \| MSG_SENDPAGE_NOTLAST \| MSG_DONTWAIT);
		if (ret <= 0)
		if (ret <= 0) {
		iov_iter_revert(&msg->msg_iter, psize);
		return ret;
		}

		frag_truesize += ret;
		if (!retransmission) {

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