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=dd63cd7876f8c6a6eb42170219c17659ff4daf42&amp;showmsg=1'>root</a>/<a href='/guix/log/tests?id=dd63cd7876f8c6a6eb42170219c17659ff4daf42&amp;showmsg=1'>tests</a>/<a href='/guix/log/tests/base16.scm?id=dd63cd7876f8c6a6eb42170219c17659ff4daf42&amp;showmsg=1'>base16.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/tests/base16.scm?id=dd63cd7876f8c6a6eb42170219c17659ff4daf42'>Collapse</a>)</th><th class='left'>Author</th></tr>
<tr class='logheader'><td><span title='2017-03-16 22:50:14 +0100'>2017-03-16</span></td><td class='logsubject'><a href='/guix/commit/tests/base16.scm?id=4c0c4db0702048488a9712dbba7cad862c667d54'>utils: Move base16 procedures to (guix base16).</a></td><td>Ludovic Courtès</td></tr>
<tr class='nohover-highlight'><td/><td colspan='3' class='logmsg'>
* guix/utils.scm (bytevector-&gt;base16-string, base16-string-&gt;bytevector):
Move to...
* guix/base16.scm: ... here.  New file.
* tests/utils.scm ("bytevector-&gt;base16-string-&gt;bytevector"): Move to...
* tests/base16.scm: ... here.  New file.
* Makefile.am (MODULES): Add guix/base16.scm.
(SCM_TESTS): Add tests/base16.scm.
* build-aux/download.scm, guix/derivations.scm,
guix/docker.scm, guix/import/snix.scm, guix/pk-crypto.scm,
guix/scripts/authenticate.scm, guix/scripts/download.scm,
guix/scripts/hash.scm, guix/store.scm, tests/hash.scm,
tests/pk-crypto.scm: Adjust imports accordingly.


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