From 0f5d2bc2007cfc73908089909af1a50ffb7e2486 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=utf8 Content-Transfer-Encoding: 8bit BugLink: http://bugs.launchpad.net/bugs/1643637 [ Upstream commit 3023898b7d4aac65987bd2f485cc22390aae6f78 ] 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 Signed-off-by: Greg Kroah-Hartman Signed-off-by: Luis Henriques --- net/socket.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/socket.c b/net/socket.c index 263b334ec5e4..0090225eeb1e 100644 --- a/net/socket.c +++ b/net/socket.c @@ -2041,6 +2041,8 @@ int __sys_sendmmsg(int fd, struct mmsghdr __user *mmsg, unsigned int vlen, if (err) break; ++datagrams; + if (msg_data_left(&msg_sys)) + break; } fput_light(sock->file, fput_needed); -- 2.39.5