Index: build_tools/cflags.xml
===================================================================
--- build_tools/cflags.xml	(revision 184273)
+++ build_tools/cflags.xml	(working copy)
@@ -9,6 +9,9 @@
 		</member>
 		<member name="MALLOC_DEBUG" displayname="Keep Track of Memory Allocations">
 		</member>
+		<member name="MALLOC_HOLD" displayname="Delay freeing memory, to find possible memory corruptors">
+			<depend>MALLOC_DEBUG</depend>
+		</member>
 		<member name="RADIO_RELAX" displayname="Relax DTMF for Radio Applications">
 		</member>
 		<member name="STATIC_BUILD" displayname="Build static binaries">
Index: main/astmm.c
===================================================================
--- main/astmm.c	(revision 184273)
+++ main/astmm.c	(working copy)
@@ -50,7 +50,8 @@
 	FUNC_STRDUP,
 	FUNC_STRNDUP,
 	FUNC_VASPRINTF,
-	FUNC_ASPRINTF
+	FUNC_ASPRINTF,
+	FUNC_FREE,
 };
 
 /* Undefine all our macros */
@@ -159,11 +160,56 @@
 {
 	int hash = HASH(ptr);
 	struct ast_region *reg, *prev = NULL;
+#ifndef MALLOC_HOLD
 	unsigned int *fence;
+#endif
 
+	if (ptr == NULL) {
+		return;
+	}
+
+#ifdef MALLOC_HOLD
+	/* Mark this segment as freed */
 	ast_mutex_lock(&reglock);
 	for (reg = regions[hash]; reg; reg = reg->next) {
 		if (reg->data == ptr) {
+			memset(ptr, reg->len, 0);
+			reg->which = FUNC_FREE;
+			reg->fence = time(NULL);
+		}
+	}
+
+	/* Delete any segment which is free for at least 120 seconds */
+	ast_mutex_lock(&reglock);
+	for (reg = regions[hash]; reg; reg = reg->next) {
+		if (reg->which == FUNC_FREE && reg->fence < time(NULL) + 120) {
+			struct ast_region *tbf = reg;
+			unsigned char *ptr;
+			if (prev) {
+				prev->next = reg->next;
+				reg = prev;
+			} else {
+				regions[hash] = reg->next;
+				reg = regions[hash];
+			}
+			for (ptr = tbf->data; ptr < tbf->data + tbf->len; ptr++) {
+				if (*ptr != 0) {
+					astmm_log("WARNING: memory written to after being freed "
+						"at %p, (originally in %s of %s, line %d\n",
+						reg->data, reg->func, reg->file, reg->lineno);
+					break;
+				}
+			}
+			free(tbf);
+		} else {
+			prev = reg;
+		}
+	}
+	ast_mutex_unlock(&reglock);
+#else
+	ast_mutex_lock(&reglock);
+	for (reg = regions[hash]; reg; reg = reg->next) {
+		if (reg->data == ptr) {
 			if (prev)
 				prev->next = reg->next;
 			else
@@ -189,6 +235,7 @@
 		astmm_log("WARNING: Freeing unused memory at %p, in %s of %s, line %d\n",	
 			ptr, func, file, lineno);
 	}
+#endif
 }
 
 void *__ast_calloc(size_t nmemb, size_t size, const char *file, int lineno, const char *func)