From: Michael R Sweet <michael.r.sweet@gmail.com>
Date: Sun, 8 Dec 2019 14:00:26 -0500
Subject: Fix a buffer underflow issue with GCC on Linux (Issue #360)

CVE-2019-19630

Origin: upstream, https://github.com/michaelrsweet/htmldoc/commit/8a129c520e90fc967351f3e165f967128a88f09c
Bug: https://github.com/michaelrsweet/htmldoc/issues/370
Bug-Debian: https://security-tracker.debian.org/tracker/CVE-2019-19630
---
 htmldoc/ps-pdf.cxx | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/htmldoc/ps-pdf.cxx b/htmldoc/ps-pdf.cxx
index 78a0183..5d96591 100644
--- a/htmldoc/ps-pdf.cxx
+++ b/htmldoc/ps-pdf.cxx
@@ -3721,7 +3721,9 @@ render_contents(tree_t *t,		/* I - Tree to parse */
          nptr < (number + sizeof(number) - 1) && width < right;
 	 width += dot_width)
       *nptr++ = '.';
-    nptr --;
+
+    if (nptr > number)
+      nptr --;
 
     strlcpy((char *)nptr, pages[hpage].page_text, sizeof(number) - (size_t)(nptr - number));