Fix CVE-2017-12836:

http://cve.mitre.org/cgi-bin/cvename.cgi?name=2017-12836
https://security-tracker.debian.org/tracker/CVE-2017-12836

Patch adpated from Debian (comments and changelog annotations removed):

https://anonscm.debian.org/cgit/collab-maint/cvs.git/commit/?h=stretch&id=41e077396e35efb6c879951f44c62dd8a1d0f094

From 41e077396e35efb6c879951f44c62dd8a1d0f094 Mon Sep 17 00:00:00 2001
From: mirabilos <m@mirbsd.org>
Date: Sat, 12 Aug 2017 03:17:18 +0200
Subject: Fix CVE-2017-12836 (Closes: #871810) for stretch

---
 debian/changelog |  6 ++++++
 src/rsh-client.c | 10 ++++++++--
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/src/rsh-client.c b/src/rsh-client.c
index fe0cfc4..1fc860d 100644
--- a/src/rsh-client.c
+++ b/src/rsh-client.c
@@ -105,6 +106,9 @@ start_rsh_server (cvsroot_t *root, struct buffer **to_server_p,
 	rsh_argv[i++] = argvport;
     }
 
+    /* Only non-option arguments from here. (CVE-2017-12836) */
+    rsh_argv[i++] = "--";
+
     rsh_argv[i++] = root->hostname;
     rsh_argv[i++] = cvs_server;
     if (readonlyfs)
@@ -189,6 +193,8 @@ start_rsh_server (cvsroot_t *root, struct buffer **to_server_p,
 		*p++ = argvport;
 	}
 
+	*p++ = "--";
+
 	*p++ = root->hostname;
 	*p++ = command;
 	*p++ = NULL;
-- 
cgit v0.12

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<div class='path'>path: <a href='/guix/log/?id=3b39ae9f4b9d2ac47383fa012f4077a0d006c66f'>root</a>/<a href='/guix/log/gnu?id=3b39ae9f4b9d2ac47383fa012f4077a0d006c66f'>gnu</a>/<a href='/guix/log/gnu/system?id=3b39ae9f4b9d2ac47383fa012f4077a0d006c66f'>system</a>/<a href='/guix/log/gnu/system/examples?id=3b39ae9f4b9d2ac47383fa012f4077a0d006c66f'>examples</a>/<a href='/guix/log/gnu/system/examples/beaglebone-black.tmpl?id=3b39ae9f4b9d2ac47383fa012f4077a0d006c66f'>beaglebone-black.tmpl</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/system/examples/beaglebone-black.tmpl?id=3b39ae9f4b9d2ac47383fa012f4077a0d006c66f&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2018-10-18 01:12:22 +0200'>2018-10-18</span></td><td><a href='/guix/commit/gnu/system/examples/beaglebone-black.tmpl?id=39d7fdce453b0ca23ecbed72048647debbaa58a6'>services: dhcp-client: Deprecate 'dhcp-client-service' procedure.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2018-05-28 13:24:11 +0200'>2018-05-28</span></td><td><a href='/guix/commit/gnu/system/examples/beaglebone-black.tmpl?id=a5acc17a3c10a3779b5b8b1a2565ef130be77e51'>file-systems: Remove 'title' field and add &lt;file-system-label&gt;.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2018-03-03 09:41:21 +0100'>2018-03-03</span></td><td><a href='/guix/commit/gnu/system/examples/beaglebone-black.tmpl?id=f850e0da8e56b8e38b0a6c49f4c0618f16c8c572'>system: beaglebone-black: Use 'initrd-modules'.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2017-12-22 08:49:57 +0100'>2017-12-22</span></td><td><a href='/guix/commit/gnu/system/examples/beaglebone-black.tmpl?id=a468f897437acfc1c70987a6df252c4735e3bf2d'>system: examples: Add missing initrd to beaglebone-black.tmpl.</a><span class='msg-avail'>...</span></td><td>Mathieu Othacehe</td></tr>
<tr><td><span title='2017-12-18 15:28:14 +0100'>2017-12-18</span></td><td><a href='/guix/commit/gnu/system/examples/beaglebone-black.tmpl?id=9f1e39d1fcca0525bc51dc0eedd11a902089bba4'>system: examples: Add a template for BeagleBone Black.</a><span class='msg-avail'>...</span></td><td>Mathieu Othacehe</td></tr>