Fix CVE-2017-7853:

https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-7853
https://savannah.gnu.org/support/index.php?109265

Patch copied from upstream source repository:

https://git.savannah.gnu.org/cgit/osip.git/commit/?id=1ae06daf3b2375c34af23083394a6f010be24a45

From 1ae06daf3b2375c34af23083394a6f010be24a45 Mon Sep 17 00:00:00 2001
From: Aymeric Moizard <amoizard@gmail.com>
Date: Tue, 21 Feb 2017 17:16:26 +0100
Subject: [PATCH]  * fix bug report: sr #109265: SIP message body length
 underflow in libosip2-4.1.0    https://savannah.gnu.org/support/?109265   
 also applicable to current latest version

---
 src/osipparser2/osip_message_parse.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/osipparser2/osip_message_parse.c b/src/osipparser2/osip_message_parse.c
index 1628c60..aa35446 100644
--- a/src/osipparser2/osip_message_parse.c
+++ b/src/osipparser2/osip_message_parse.c
@@ -784,6 +784,12 @@ msg_osip_body_parse (osip_message_t * sip, const char *start_of_buf, const char
     if ('\n' == start_of_body[0] || '\r' == start_of_body[0])
       start_of_body++;
 
+    /* if message body is empty or contains a single CR/LF */
+    if (end_of_body <= start_of_body) {
+      osip_free (sep_boundary);
+      return OSIP_SYNTAXERROR;
+    }
+
     body_len = end_of_body - start_of_body;
 
     /* Skip CR before end boundary. */
-- 
2.13.1

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<div class='path'>path: <a href='/guix/log/?id=61521e1a7a1ee403f69130ef54ca00fb37173859'>root</a>/<a href='/guix/log/gnu?id=61521e1a7a1ee403f69130ef54ca00fb37173859'>gnu</a>/<a href='/guix/log/gnu/artwork.scm?id=61521e1a7a1ee403f69130ef54ca00fb37173859'>artwork.scm</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/artwork.scm?id=61521e1a7a1ee403f69130ef54ca00fb37173859&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2019-06-10 23:11:07 +0200'>2019-06-10</span></td><td><a href='/guix/commit/gnu/artwork.scm?id=226a3605d6cabeb71247a732a99d625c9cfafa74'>artwork: Update snapshot to 2f2fe74.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/artwork.scm (%artwork-repository): Update to 2f2fe74.

Signed-off-by: Ludovic Courtès &lt;ludo@gnu.org&gt;
</span></span></td><td>Diego Nicola Barbato</td></tr>
<tr><td><span title='2019-03-05 23:08:53 +0100'>2019-03-05</span></td><td><a href='/guix/commit/gnu/artwork.scm?id=5387971a9ecf511e1dbbac992af3808437e58d56'>artwork: Update snapshot to b975164.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/artwork.scm (%artwork-repository): Update to b975164.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2019-02-10 23:25:01 +0100'>2019-02-10</span></td><td><a href='/guix/commit/gnu/artwork.scm?id=5e6a5aeebd7b735e5d5f2eed496cc1c7e8a5b4c9'>artwork: Update snapshot to e951905.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/artwork.scm (%artwork-repository): Update to e951905.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2018-11-05 00:08:47 +0100'>2018-11-05</span></td><td><a href='/guix/commit/gnu/artwork.scm?id=688d1a01e45eb1277a6337987bfd53f3fe3caaec'>artwork: Clone over HTTPS.</a><span class='msg-avail'>...<span class='msg-tooltip'>Suggested by Leo Famulari &lt;leo@famulari.name&gt;
at &lt;https://lists.gnu.org/archive/html/help-guix/2018-11/msg00039.html&gt;.

* gnu/artwork.scm (%artwork-repository): Switch to HTTPS URL.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2017-06-07 15:58:16 -0400'>2017-06-07</span></td><td><a href='/guix/commit/gnu/artwork.scm?id=94db92f78ec9c849f9c8da05d4d35356909f9fbe'>artwork: Use a descriptive name for the source directory.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/artwork.scm (%artwork-repository): Set a descriptive file-name and
use the full commit hash when fetching.
</span></span></td><td>Leo Famulari</td></tr>