linux-kernel - [PATCH 4.9 51/61] rxrpc: Fix sendmsg() returning EPIPE due to recvmsg() returning ENODATA

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Message-Id: <20200730074423.305397265@linuxfoundation.org>
Date:   Thu, 30 Jul 2020 10:05:09 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, David Howells <dhowells@...hat.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.9 51/61] rxrpc: Fix sendmsg() returning EPIPE due to recvmsg() returning ENODATA

From: David Howells <dhowells@...hat.com>

[ Upstream commit 639f181f0ee20d3249dbc55f740f0167267180f0 ]

rxrpc_sendmsg() returns EPIPE if there's an outstanding error, such as if
rxrpc_recvmsg() indicating ENODATA if there's nothing for it to read.

Change rxrpc_recvmsg() to return EAGAIN instead if there's nothing to read
as this particular error doesn't get stored in ->sk_err by the networking
core.

Also change rxrpc_sendmsg() so that it doesn't fail with delayed receive
errors (there's no way for it to report which call, if any, the error was
caused by).

Fixes: 17926a79320a ("[AF_RXRPC]: Provide secure RxRPC sockets for use by userspace and kernel both")
Signed-off-by: David Howells <dhowells@...hat.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/rxrpc/recvmsg.c |    2 +-
 net/rxrpc/sendmsg.c |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

--- a/net/rxrpc/recvmsg.c
+++ b/net/rxrpc/recvmsg.c
@@ -439,7 +439,7 @@ try_again:
 	    list_empty(&rx->recvmsg_q) &&
 	    rx->sk.sk_state != RXRPC_SERVER_LISTENING) {
 		release_sock(&rx->sk);
-		return -ENODATA;
+		return -EAGAIN;
 	}
 
 	if (list_empty(&rx->recvmsg_q)) {
--- a/net/rxrpc/sendmsg.c
+++ b/net/rxrpc/sendmsg.c
@@ -191,7 +191,7 @@ static int rxrpc_send_data(struct rxrpc_
 	/* this should be in poll */
 	sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
 
-	if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
+	if (sk->sk_shutdown & SEND_SHUTDOWN)
 		return -EPIPE;
 
 	more = msg->msg_flags & MSG_MORE;