From 3023898b7d4aac65987bd2f485cc22390aae6f78 Mon Sep 17 00:00:00 2001 From: Soheil Hassas Yeganeh Date: Fri, 4 Nov 2016 15:36:49 -0400 Subject: [PATCH] sock: fix sendmmsg for partial sendmsg MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Do not send the next message in sendmmsg for partial sendmsg invocations. sendmmsg assumes that it can continue sending the next message when the return value of the individual sendmsg invocations is positive. It results in corrupting the data for TCP, SCTP, and UNIX streams. For example, sendmmsg([["abcd"], ["efgh"]]) can result in a stream of "aefgh" if the first sendmsg invocation sends only the first byte while the second sendmsg goes through. Datagram sockets either send the entire datagram or fail, so this patch affects only sockets of type SOCK_STREAM and SOCK_SEQPACKET. Fixes: 228e548e6020 ("net: Add sendmmsg socket system call") Signed-off-by: Soheil Hassas Yeganeh Signed-off-by: Eric Dumazet Signed-off-by: Willem de Bruijn Signed-off-by: Neal Cardwell Acked-by: Maciej Żenczykowski Signed-off-by: David S. Miller --- net/socket.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/socket.c b/net/socket.c index 5a9bf5ee2464..272518b087c8 100644 --- a/net/socket.c +++ b/net/socket.c @@ -2038,6 +2038,8 @@ int __sys_sendmmsg(int fd, struct mmsghdr __user *mmsg, unsigned int vlen, if (err) break; ++datagrams; + if (msg_data_left(&msg_sys)) + break; cond_resched(); }