Fix CVE-2017-17787:

https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-17787
https://bugzilla.gnome.org/show_bug.cgi?id=790853

Patch copied from upstream source repository:

https://git.gnome.org/browse/gimp/commit/?id=87ba505fff85989af795f4ab6a047713f4d9381d

From 87ba505fff85989af795f4ab6a047713f4d9381d Mon Sep 17 00:00:00 2001
From: Jehan <jehan@girinstud.io>
Date: Thu, 21 Dec 2017 12:49:41 +0100
Subject: [PATCH] Bug 790853 - (CVE-2017-17787) heap overread in psp importer.

As any external data, we have to check that strings being read at fixed
length are properly nul-terminated.

(cherry picked from commit eb2980683e6472aff35a3117587c4f814515c74d)
---
 plug-ins/common/file-psp.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/plug-ins/common/file-psp.c b/plug-ins/common/file-psp.c
index 4cbafe37b1..e350e4d88d 100644
--- a/plug-ins/common/file-psp.c
+++ b/plug-ins/common/file-psp.c
@@ -890,6 +890,12 @@ read_creator_block (FILE     *f,
               g_free (string);
               return -1;
             }
+          if (string[length - 1] != '\0')
+            {
+              g_message ("Creator keyword data not nul-terminated");
+              g_free (string);
+              return -1;
+            }
           switch (keyword)
             {
             case PSP_CRTR_FLD_TITLE:
-- 
2.15.1

