Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1332335

[PATCH net] af_unix: Guard against other == sk in unix_dgram_sendmsg

Show all headers | View raw

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 <pmhahn@pmhahn.de>
Signed-off-by: Rainer Weikusat <rweikusat@mobileactivedefense.com>
---
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 29be035..f1ca279 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -1781,7 +1781,12 @@ 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);
 

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Re: Bug 4.1.16: self-detected stall in net/unix/? Philipp Hahn <pmhahn@pmhahn.de> - 2016-02-11 14:50 +0100
  Re: Bug 4.1.16: self-detected stall in net/unix/? Rainer Weikusat <rweikusat@mobileactivedefense.com> - 2016-02-11 17:00 +0100
    Re: Bug 4.1.16: self-detected stall in net/unix/? Ben Hutchings <ben@decadent.org.uk> - 2016-02-11 18:10 +0100
      Re: Bug 4.1.16: self-detected stall in net/unix/? Rainer Weikusat <rweikusat@mobileactivedefense.com> - 2016-02-11 18:50 +0100
        Re: Bug 4.1.16: self-detected stall in net/unix/? Rainer Weikusat <rweikusat@mobileactivedefense.com> - 2016-02-11 19:00 +0100
        Re: Bug 4.1.16: self-detected stall in net/unix/? Rainer Weikusat <rweikusat@mobileactivedefense.com> - 2016-02-11 19:40 +0100
          [PATCH net] af_unix: Guard against other == sk in unix_dgram_sendmsg Rainer Weikusat <rweikusat@mobileactivedefense.com> - 2016-02-11 20:40 +0100
            Re: [PATCH net] af_unix: Guard against other == sk in  unix_dgram_sendmsg Philipp Hahn <pmhahn@pmhahn.de> - 2016-02-12 10:20 +0100
              Re: [PATCH net] af_unix: Guard against other == sk in unix_dgram_sendmsg Rainer Weikusat <rweikusat@mobileactivedefense.com> - 2016-02-12 14:30 +0100
                Re: [PATCH net] af_unix: Guard against other == sk in  unix_dgram_sendmsg Ben Hutchings <ben@decadent.org.uk> - 2016-02-12 21:00 +0100
                Re: [PATCH net] af_unix: Guard against other == sk in unix_dgram_sendmsg Rainer Weikusat <rweikusat@mobileactivedefense.com> - 2016-02-12 21:20 +0100
                Re: [PATCH net] af_unix: Guard against other == sk in  unix_dgram_sendmsg Ben Hutchings <ben@decadent.org.uk> - 2016-02-12 21:50 +0100
                Re: [PATCH net] af_unix: Guard against other == sk in unix_dgram_sendmsg Rainer Weikusat <rweikusat@mobileactivedefense.com> - 2016-02-12 22:10 +0100
            Re: [PATCH net] af_unix: Guard against other == sk in  unix_dgram_sendmsg David Miller <davem@davemloft.net> - 2016-02-16 19:00 +0100

csiph-web