Bug#602566: dvi2ps segfault based on bug in libkpathsea

[Norbert Preining <preining@logic.at>]

Dear all, esp Karl,

Details can be found in Debian bug report 602566
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=602566

dvi2ps dumps core on a simple dvi file on mipsel arch, quoting an
email in the bug report:
> The bug seems to come from libkpathsea5 and not from dvi2ps. It exists
> on all platforms (at least also on AMD64) but does not trigger a
> segfault. It comes from the kpse_set_suffixes function in the
> libkpathsea compatibility API which calls the kpathsea_set_suffixes
> function and passes to it its variable list of arguments. This operation
> is invalid in C.

In the bug report there is also a backtrace of the segfault and
two patches by Mathias Kende, quoting his email:
> The first patch duplicates some code in tex-file.c (approx. 15 lines),
> but is smaller and simpler. The second creates a helper function which
> reads properly a "va_list" list of arguments. Choose your preferred one.

I attach the two patches, both apply (with some fuzzyness) to current
sources in TeX Live.

What do others think?

Best wishes

Norbert
------------------------------------------------------------------------
Norbert Preining            preining@{jaist.ac.jp, logic.at, debian.org}
JAIST, Japan                                 TeX Live & Debian Developer
DSA: 0x09C5B094   fp: 14DF 2E6C 0307 BE6D AD76  A9C0 D2BF 4AA3 09C5 B094
------------------------------------------------------------------------
BURNT YATES
Condition to which yates (q.v.) will suddenly pass without any
apparent interviewing period, after the spirit of the throckmorton
(q.v.) has finally been summoned by incessant throcking (q.v.)
			--- Douglas Adams, The Meaning of Liff

--- a/texlive-bin-2009/texk/kpathsea/tex-file.c	2009-06-23 15:50:13.000000000 +0200
+++ b/texlive-bin-2009/texk/kpathsea/tex-file.c	2010-11-08 15:41:50.000000000 +0100
@@ -346,20 +346,34 @@
   (*list)[count] = NULL;
 }
 
-
 #if defined (KPSE_COMPAT_API)
+/* it is impossible to pass around a list of (variable) arguments.  */
 void
 kpse_set_suffixes (kpse_file_format_type format,
                    boolean alternate, ...)
 {
+  const_string **list;
+  const_string s;
+  int count = 0;
   va_list ap;
+
+  if (alternate) {
+      list = &(kpse_def->format_info[format].alt_suffix);
+  } else {
+      list = &(kpse_def->format_info[format].suffix);
+  }
+
   va_start (ap, alternate);
-  kpathsea_set_suffixes (kpse_def, format, alternate, ap);
+  while ((s = va_arg (ap, string)) != NULL) {
+    count++;
+    XRETALLOC (*list, count + 1, const_string);
+    (*list)[count - 1] = s;
+  }
   va_end (ap);
+  (*list)[count] = NULL;
 }
 #endif
 
-
 /* The path spec we are defining, one element of the global array.  */
 #define FMT_INFO (kpse->format_info[format])
 /* Call kpse_set_add_suffixes.  */

--- a/texlive-bin-2009/texk/kpathsea/tex-file.c	2010-11-08 16:37:04.000000000 +0100
+++ b/texlive-bin-2009/texk/kpathsea/tex-file.c	2010-11-08 16:41:08.000000000 +0100
@@ -321,14 +321,13 @@
 /* Some file types have more than one suffix, and sometimes it is
    convenient to modify the list of searched suffixes.  */ 
 
-void
-kpathsea_set_suffixes (kpathsea kpse, kpse_file_format_type format,
-  boolean alternate, ...)
+static void
+kpathsea_set_suffixes_va_list(kpathsea kpse, kpse_file_format_type format,
+  boolean alternate, va_list ap)
 {
   const_string **list;
   const_string s;
   int count = 0;
-  va_list ap;
 
   if (alternate) {
       list = &(kpse->format_info[format].alt_suffix);
@@ -336,16 +335,24 @@
       list = &(kpse->format_info[format].suffix);
   }
 
-  va_start (ap, alternate);
   while ((s = va_arg (ap, string)) != NULL) {
     count++;
     XRETALLOC (*list, count + 1, const_string);
     (*list)[count - 1] = s;
   }
-  va_end (ap);
   (*list)[count] = NULL;
 }
 
+void
+kpathsea_set_suffixes (kpathsea kpse, kpse_file_format_type format,
+  boolean alternate, ...)
+{
+  va_list ap;
+  va_start (ap, alternate);
+  kpathsea_set_suffixes_va_list (kpse, format, alternate, ap);
+  va_end (ap);
+}
+
 
 #if defined (KPSE_COMPAT_API)
 void
@@ -354,7 +361,7 @@
 {
   va_list ap;
   va_start (ap, alternate);
-  kpathsea_set_suffixes (kpse_def, format, alternate, ap);
+  kpathsea_set_suffixes_va_list (kpse_def, format, alternate, ap);
   va_end (ap);
 }
 #endif