[Bug 1801128] Re: OpenSSH 7.7 -w tunnel bug

[Adam Jacobs]

For simplicity, here's the patch that fixes this bug (and is included in
openssh 7.8):

diff --git a/openbsd-compat/port-net.c b/openbsd-compat/port-net.c
index 7050629c..bb535626 100644
--- a/openbsd-compat/port-net.c
+++ b/openbsd-compat/port-net.c
@@ -185,7 +185,7 @@ sys_tun_open(int tun, int mode, char **ifname)
 	else
 		debug("%s: %s mode %d fd %d", __func__, ifr.ifr_name, mode, fd);
 
-	if (ifname != NULL && (*ifname = strdup(ifr.ifr_name)))
+	if (ifname != NULL && (*ifname = strdup(ifr.ifr_name)) == NULL)
 		goto failed;
 
 	return (fd);
@@ -272,7 +272,7 @@ sys_tun_open(int tun, int mode, char **ifname)
 			goto failed;
 	}
 
-	if (ifname != NULL && (*ifname = strdup(ifr.ifr_name)))
+	if (ifname != NULL && (*ifname = strdup(ifr.ifr_name)) == NULL)
 		goto failed;
 
 	close(sock);

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https://bugs.launchpad.net/bugs/1801128

Title:
  OpenSSH 7.7 -w tunnel bug

Status in openssh package in Ubuntu:
  New

Bug description:
  Just upgraded to cosmic, which picks up OpenSSH 7.7.

  OpenSSH 7.7 has known bug
  https://bugzilla.mindrot.org/show_bug.cgi?id=2855 which is fixed in
  OpenSSH 7.8.  It's a regression that completely breaks -w tunneling.

  The OpenSSH bug contains a trivial two-line patch to fix the bug.  I
  downloaded the Ubuntu openssh package source, applied the patch and
  rebuilt, and can confirm that is does fix the problem.

  Any chance we could get this patch backported to Cosmic?

  ProblemType: Bug
  DistroRelease: Ubuntu 18.10
  Package: openssh-client 1:7.7p1-4
  ProcVersionSignature: Ubuntu 4.18.0-10.11-generic 4.18.12
  Uname: Linux 4.18.0-10-generic x86_64
  ApportVersion: 2.20.10-0ubuntu13
  Architecture: amd64
  Date: Thu Nov  1 09:36:16 2018
  ProcEnviron:
   TERM=xterm-256color
   PATH=(custom, no user)
   XDG_RUNTIME_DIR=<set>
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  RelatedPackageVersions:
   ssh-askpass       N/A
   libpam-ssh        N/A
   keychain          N/A
   ssh-askpass-gnome N/A
  SSHClientVersion: OpenSSH_7.7p1 Ubuntu-4, OpenSSL 1.0.2n  7 Dec 2017
  SourcePackage: openssh
  UpgradeStatus: Upgraded to cosmic on 2018-11-01 (0 days ago)

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