Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S937161AbdCJNT3 (ORCPT ); Fri, 10 Mar 2017 08:19:29 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:43657 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933605AbdCJLw5 (ORCPT ); Fri, 10 Mar 2017 06:52:57 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Neal Cardwell" , "Soheil Hassas Yeganeh" , "Eric Dumazet" , "David S. Miller" , "Willem de Bruijn" , "Maciej =?UTF-8?Q?=C5=BBenczykowski?=" Date: Fri, 10 Mar 2017 11:46:23 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 338/370] sock: fix sendmmsg for partial sendmsg In-Reply-To: X-SA-Exim-Connect-IP: 82.70.136.246 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3455 Lines: 104 3.16.42-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Soheil Hassas Yeganeh [ 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 [bwh: Backported to 3.16: we don't have the iov_iter API, so make ___sys_sendmsg() calculate and write back the remaining length] Signed-off-by: Ben Hutchings --- net/socket.c | 2 ++ 1 file changed, 2 insertions(+) --- a/net/socket.c +++ b/net/socket.c @@ -1998,7 +1998,7 @@ static int copy_msghdr_from_user(struct static int ___sys_sendmsg(struct socket *sock, struct msghdr __user *msg, struct msghdr *msg_sys, unsigned int flags, - struct used_address *used_address) + struct used_address *used_address, int *residue) { struct compat_msghdr __user *msg_compat = (struct compat_msghdr __user *)msg; @@ -2097,6 +2097,8 @@ static int ___sys_sendmsg(struct socket memcpy(&used_address->name, msg_sys->msg_name, used_address->name_len); } + if (residue && err >= 0) + *residue = total_len - err; out_freectl: if (ctl_buf != ctl) @@ -2122,7 +2124,7 @@ long __sys_sendmsg(int fd, struct msghdr if (!sock) goto out; - err = ___sys_sendmsg(sock, msg, &msg_sys, flags, NULL); + err = ___sys_sendmsg(sock, msg, &msg_sys, flags, NULL, NULL); fput_light(sock->file, fput_needed); out: @@ -2149,6 +2151,7 @@ int __sys_sendmmsg(int fd, struct mmsghd struct compat_mmsghdr __user *compat_entry; struct msghdr msg_sys; struct used_address used_address; + int residue; if (vlen > UIO_MAXIOV) vlen = UIO_MAXIOV; @@ -2167,7 +2170,8 @@ int __sys_sendmmsg(int fd, struct mmsghd while (datagrams < vlen) { if (MSG_CMSG_COMPAT & flags) { err = ___sys_sendmsg(sock, (struct msghdr __user *)compat_entry, - &msg_sys, flags, &used_address); + &msg_sys, flags, &used_address, + &residue); if (err < 0) break; err = __put_user(err, &compat_entry->msg_len); @@ -2175,7 +2179,8 @@ int __sys_sendmmsg(int fd, struct mmsghd } else { err = ___sys_sendmsg(sock, (struct msghdr __user *)entry, - &msg_sys, flags, &used_address); + &msg_sys, flags, &used_address, + &residue); if (err < 0) break; err = put_user(err, &entry->msg_len); @@ -2185,6 +2190,8 @@ int __sys_sendmmsg(int fd, struct mmsghd if (err) break; ++datagrams; + if (residue) + break; } fput_light(sock->file, fput_needed);