Fix a buffer underflow issue with GCC on Linux (Issue #360)

michaelrsweet · Dec 8, 2019 · 8a129c5 · 8a129c5
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diff --git a/CHANGES.md b/CHANGES.md
@@ -1,6 +1,7 @@
 # Changes in HTMLDOC v1.9.8
 
 - Fixed a paragraph formatting issue with large inline images (Issue #369)
+- Fixed a buffer underflow issue (Issue #370)
 
 
 # Changes in HTMLDOC v1.9.7

diff --git a/htmldoc/ps-pdf.cxx b/htmldoc/ps-pdf.cxx
@@ -3761,7 +3761,9 @@ 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));