From 50acf9e6e34a14148d6a8c715c79b1cb013f4f3d 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 Change-Id: I4ebef6a390df3487903b166b837e34c653e01cb2 Signed-off-by: Amit Pundir --- 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 ef05cd9403d4..8badff627fef 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -1765,7 +1765,12 @@ restart_locked: 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);