[PATCH 3.18 40/49] af_unix: Guard against other == sk in unix_dgram_sendmsg

From	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Newsgroups	linux.kernel
Subject	[PATCH 3.18 40/49] af_unix: Guard against other == sk in unix_dgram_sendmsg
Date	2017-05-18 15:30 +0200
Message-ID	<tItFa-37o-73@gated-at.bofh.it> (permalink)
References	<tItvr-33n-5@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Rainer Weikusat <rweikusat@mobileactivedefense.com>

commit a5527dda344fff0514b7989ef7a755729769daa1 upstream.

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>
Tested-by: Philipp Hahn <pmhahn@pmhahn.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 net/unix/af_unix.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -1722,7 +1722,12 @@ 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);

Thread

[PATCH 3.18 00/49] 3.18.54-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-18 15:20 +0200
  [PATCH 3.18 22/49] SMB3: Work around mount failure when using SMB3 dialect to Macs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-18 15:20 +0200
  [PATCH 3.18 01/49] target/fileio: Fix zero-length READ and WRITE handling Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-18 15:20 +0200
  [PATCH 3.18 41/49] ppp: defer netns reference release for ppp channel Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-18 15:20 +0200
  [PATCH 3.18 09/49] staging: comedi: jr3_pci: cope with jiffies wraparound Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-18 15:20 +0200
  [PATCH 3.18 31/49] perf: Fix event->ctx locking Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-18 15:20 +0200
  [PATCH 3.18 11/49] usb: hub: Do not attempt to autosuspend disconnected devices Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-18 15:20 +0200
  [PATCH 3.18 07/49] staging: gdm724x: gdm_mux: fix use-after-free on module unload Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-18 15:20 +0200
  [PATCH 3.18 44/49] sched: panic on corrupted stack end Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-18 15:20 +0200
  [PATCH 3.18 06/49] staging: vt6656: use off stack for out buffer USB transfers. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-18 15:20 +0200
  [PATCH 3.18 08/49] staging: comedi: jr3_pci: fix possible null pointer dereference Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-18 15:30 +0200
  [PATCH 3.18 32/49] arm64: perf: reject groups spanning multiple HW PMUs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-18 15:30 +0200
  [PATCH 3.18 42/49] HID: core: prevent out-of-bound readings Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-18 15:30 +0200
  [PATCH 3.18 05/49] staging: vt6656: use off stack for in buffer USB transfers. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-18 15:30 +0200
  [PATCH 3.18 04/49] USB: Proper handling of Race Condition when two USB class drivers try to call init_usb_class simultaneously Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-18 15:30 +0200
  [PATCH 3.18 17/49] IB/mlx4: Fix ib device initialization error flow Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-18 15:30 +0200
  [PATCH 3.18 39/49] ipv6: sctp: fix lockdep splat in sctp_v6_get_dst() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-18 15:30 +0200
  [PATCH 3.18 33/49] perf: Fix race in swevent hash Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-18 15:30 +0200
  [PATCH 3.18 26/49] md/raid1: avoid reusing a resync bio after error handling. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-18 15:30 +0200
  [PATCH 3.18 38/49] ipv6: sctp: add rcu protection around np->opt Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-18 15:30 +0200
  [PATCH 3.18 29/49] Bluetooth: Fix user channel for 32bit userspace on 64bit kernel Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-18 15:30 +0200
  [PATCH 3.18 37/49] sg: Fix double-free when drives detach during SG_IO Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-18 15:30 +0200
  [PATCH 3.18 36/49] ext4: fix potential use after free in __ext4_journal_stop Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-18 15:30 +0200
  [PATCH 3.18 18/49] fs/xattr.c: zero out memory copied to userspace in getxattr Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-18 15:30 +0200
  [PATCH 3.18 03/49] USB: serial: ftdi_sio: add device ID for Microsemi/Arrow SF2PLUS Dev Kit Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-18 15:30 +0200
  [PATCH 3.18 34/49] ASN.1: Fix non-match detection failure on data overrun Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-18 15:30 +0200
  [PATCH 3.18 21/49] Set unicode flag on cifs echo request to avoid Mac error Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-18 15:30 +0200
  [PATCH 3.18 45/49] ALSA: seq: Fix race at timer setup and close Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-18 15:30 +0200
  [PATCH 3.18 30/49] arm64: make sys_call_table const Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-18 15:30 +0200
  [PATCH 3.18 25/49] padata: free correct variable Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-18 15:30 +0200
  [PATCH 3.18 28/49] serial: omap: suspend device on probe errors Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-18 15:30 +0200
  [PATCH 3.18 40/49] af_unix: Guard against other == sk in unix_dgram_sendmsg Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-18 15:30 +0200
  [PATCH 3.18 02/49] usb: host: xhci: print correct command ring address Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-18 15:40 +0200
  [PATCH 3.18 12/49] usb: misc: legousbtower: Fix buffers on stack Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-18 15:40 +0200
  [PATCH 3.18 20/49] fs/block_dev: always invalidate cleancache in invalidate_bdev() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-18 15:40 +0200
  [PATCH 3.18 16/49] IB/IPoIB: ibX: failed to create mcg debug file Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-18 15:40 +0200
  [PATCH 3.18 14/49] um: Fix PTRACE_POKEUSER on x86_64 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-18 15:40 +0200
  Re: [PATCH 3.18 00/49] 3.18.54-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2017-05-18 19:30 +0200
  Re: [PATCH 3.18 00/49] 3.18.54-stable review Guenter Roeck <linux@roeck-us.net> - 2017-05-19 03:10 +0200

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