Fix CVE-2017-7376:

https://bugzilla.gnome.org/show_bug.cgi?id=780690 (not yet public)
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-7376
https://security-tracker.debian.org/tracker/CVE-2017-7376

Patch copied from upstream source repository:

https://git.gnome.org/browse/libxml2/commit/?id=5dca9eea1bd4263bfa4d037ab2443de1cd730f7e

From 5dca9eea1bd4263bfa4d037ab2443de1cd730f7e Mon Sep 17 00:00:00 2001
From: Daniel Veillard <veillard@redhat.com>
Date: Fri, 7 Apr 2017 17:13:28 +0200
Subject: [PATCH] Increase buffer space for port in HTTP redirect support

For https://bugzilla.gnome.org/show_bug.cgi?id=780690

nanohttp.c: the code wrongly assumed a short int port value.
---
 nanohttp.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/nanohttp.c b/nanohttp.c
index e109ad75..373425de 100644
--- a/nanohttp.c
+++ b/nanohttp.c
@@ -1423,9 +1423,9 @@ retry:
     if (ctxt->port != 80) {
 	/* reserve space for ':xxxxx', incl. potential proxy */
 	if (proxy)
-	    blen += 12;
+	    blen += 17;
 	else
-	    blen += 6;
+	    blen += 11;
     }
     bp = (char*)xmlMallocAtomic(blen);
     if ( bp == NULL ) {
-- 
2.14.1

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