From 5bed19c9f463f9078063363779548c50aea271a0 Mon Sep 17 00:00:00 2001 From: Rainer Weikusat Date: Thu, 11 Feb 2016 19:37:27 +0000 Subject: [PATCH] UPSTREAM: af_unix: Guard against other == sk in unix_dgram_sendmsg (cherry picked from commit a5527dda344fff0514b7989ef7a755729769daa1) The unix_dgram_sendmsg routine use the following test if (unlikely(unix_peer(other) != sk && unix_recvq_full(other))) { to determine if sk and other are in an n:1 association (either established via connect or by using sendto to send messages to an unrelated socket identified by address). This isn't correct as the specified address could have been bound to the sending socket itself or because this socket could have been connected to itself by the time of the unix_peer_get but disconnected before the unix_state_lock(other). In both cases, the if-block would be entered despite other == sk which might either block the sender unintentionally or lead to trying to unlock the same spin lock twice for a non-blocking send. Add a other != sk check to guard against this. Fixes: 7d267278a9ec ("unix: avoid use-after-free in ep_remove_wait_queue") Reported-By: Philipp Hahn Signed-off-by: Rainer Weikusat Tested-by: Philipp Hahn Signed-off-by: David S. Miller Fixes: Change-Id: Ia374ee061195088f8c777940baa75cedbe897f4e ("UPSTREAM: unix: avoid use-after-free in ep_remove_wait_queue") Change-Id: I4ebef6a390df3487903b166b837e34c653e01cb2 Signed-off-by: Amit Pundir Bug: 29119002 --- net/unix/af_unix.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 5e6323792a5e0..204bee47aa10c 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -1701,7 +1701,12 @@ static int unix_dgram_sendmsg(struct kiocb *kiocb, struct socket *sock, goto out_unlock; } - if (unlikely(unix_peer(other) != sk && unix_recvq_full(other))) { + /* other == sk && unix_peer(other) != sk if + * - unix_peer(sk) == NULL, destination address bound to sk + * - unix_peer(sk) == sk by time of get but disconnected before lock + */ + if (other != sk && + unlikely(unix_peer(other) != sk && unix_recvq_full(other))) { if (timeo) { timeo = unix_wait_for_peer(other, timeo);