(align): If the argument SIZE would overflow

__malloc_ptrdiff_t, fail right away.

2 files changed, 13 insertions, 1 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index ed4535c28d9..048eedf14fa 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,8 @@
+2001-04-09  Eli Zaretskii  <eliz@is.elta.co.il>
+
+        * gmalloc.c (align): If the argument SIZE would overflow
+        __malloc_ptrdiff_t, fail right away.
+
 2001-04-06  Gerd Moellmann  <gerd@gnu.org>
 
         * xfns.c (compute_tip_xy): Add parameters WIDTH and HEIGHT.
diff --git a/src/gmalloc.c b/src/gmalloc.c
index 751e90baf13..3508304da33 100644
--- a/src/gmalloc.c
+++ b/src/gmalloc.c
@@ -437,7 +437,14 @@ align (size)
   __ptr_t result;
   unsigned long int adj;
 
-  result = (*__morecore) (size);
+  /* align accepts an unsigned argument, but __morecore accepts a
+     signed one.  This could lead to trouble if SIZE overflows a
+     signed int type accepted by __morecore.  We just punt in that
+     case, since they are requesting a ludicrous amount anyway.  */
+  if ((__malloc_ptrdiff_t)size < 0)
+    result = 0;
+  else
+    result = (*__morecore) (size);
   adj = (unsigned long int) ((unsigned long int) ((char *) result -
                                                   (char *) NULL)) % BLOCKSIZE;
   if (adj != 0)