[PATCH] dfa: more heap-allocation-related overflow protection

[Jim Meyering]

I did a more thorough search through dfa.c for potential heap
allocation problems and found two more.  This fixes them:

>From bfd71eeff179f1ddeaefb63860b58941ea95a14f Mon Sep 17 00:00:00 2001
From: Jim Meyering <address@hidden>
Date: Tue, 21 Jun 2011 10:14:45 +0200
Subject: [PATCH] dfa: more heap-allocation-related overflow protection

* src/dfa.c (enlist): Use xnrealloc, not realloc.
Also, remove unnecessary cast-to-(char *).
(dfamust): Use xnmalloc, not malloc.  Before, this code would
return upon malloc failure (xnmalloc exits upon failure), but
later, via the *ALLOC macros, it could already exit, so this
new potential exit point is nothing new.  The same applies
to enlist, since it is called only through dfamust.
---
 src/dfa.c |    8 ++------
 1 files changed, 2 insertions(+), 6 deletions(-)

diff --git a/src/dfa.c b/src/dfa.c
index 0fc6c55..10825f7 100644
--- a/src/dfa.c
+++ b/src/dfa.c
@@ -3712,9 +3712,7 @@ enlist (char **cpp, char *new, size_t len)
         cpp[i] = NULL;
       }
   /* Add the new string. */
-  cpp = realloc((char *) cpp, (i + 2) * sizeof *cpp);
-  if (cpp == NULL)
-    return NULL;
+  cpp = xnrealloc(cpp, i + 2, sizeof *cpp);
   cpp[i] = new;
   cpp[i + 1] = NULL;
   return cpp;
@@ -3839,9 +3837,7 @@ dfamust (struct dfa *d)

   result = empty_string;
   exact = 0;
-  musts = malloc((d->tindex + 1) * sizeof *musts);
-  if (musts == NULL)
-    return;
+  musts = xnmalloc(d->tindex + 1, sizeof *musts);
   mp = musts;
   for (i = 0; i <= d->tindex; ++i)
     mp[i] = must0;
--
1.7.6.rc2.295.gb63f3