Make all combinations of G, P, J and zero-fill work with as little

effort as possible in most cases; ok djm@

1 files changed, 20 insertions, 5 deletions

diff --git a/src/lib/libc/stdlib/malloc.c b/src/lib/libc/stdlib/malloc.c
index 1cbe7fa084..be80640e81 100644
--- a/src/lib/libc/stdlib/malloc.c
+++ b/src/lib/libc/stdlib/malloc.c
@@ -1,4 +1,4 @@
-/*      $OpenBSD: malloc.c,v 1.97 2008/08/23 07:49:38 djm Exp $ */
+/*      $OpenBSD: malloc.c,v 1.98 2008/08/25 17:56:17 otto Exp $        */
 /*
  * Copyright (c) 2008 Otto Moerbeek <otto@drijf.net>
  *
@@ -1078,8 +1078,6 @@ omalloc(size_t sz, int zero_fill)
                         errno = ENOMEM;
                         return NULL;
                 }
-                if (malloc_junk)
-                        memset(p + sz, SOME_JUNK, psz - sz);
                 if (malloc_guard) {
                         if (mprotect((char *)p + psz - malloc_guard,
                             malloc_guard, PROT_NONE))
@@ -1087,11 +1085,28 @@ omalloc(size_t sz, int zero_fill)
                         malloc_guarded += malloc_guard;
                 }
 
-                /* shift towards the end */
                 if (malloc_move &&
-                    sz - malloc_guard < MALLOC_PAGESIZE - MALLOC_MINSIZE)
+                    sz - malloc_guard < MALLOC_PAGESIZE - MALLOC_MINSIZE) {
+                        /* fill whole allocation */
+                        if (malloc_junk)
+                                memset(p, SOME_JUNK, psz - malloc_guard);
+                        /* shift towards the end */
                         p = ((char *)p) + ((MALLOC_PAGESIZE - MALLOC_MINSIZE -
                             (sz - malloc_guard)) & ~(MALLOC_MINSIZE-1));
+                        /* fill zeros if needed and overwritten above */
+                        if (zero_fill && malloc_junk)
+                                memset(p, 0, sz - malloc_guard);
+                } else {
+                        if (malloc_junk) {
+                                if (zero_fill)
+                                        memset(p + sz - malloc_guard,
+                                            SOME_JUNK, psz - sz);
+                                else
+                                        memset(p,
+                                            SOME_JUNK, psz - malloc_guard);
+                        }
+                }
+
         } else {
                 /* takes care of SOME_JUNK */
                 p = malloc_bytes(&g_pool, sz);