1 files changed, 67 insertions, 0 deletions
diff --git a/malloc/mallocbug.c b/malloc/mallocbug.c
new file mode 100644
index 0000000000..84a6387954
--- /dev/null
+++ b/malloc/mallocbug.c
@@ -0,0 +1,67 @@
+/* Reproduce a GNU malloc bug.  */
+#include <malloc.h>
+#include <stdio.h>
+#include <string.h>
+
+#define size_t unsigned int
+
+int
+main (int argc, char *argv[])
+{
+  char *dummy0;
+  char *dummy1;
+  char *fill_info_table1;
+  char *over_top;
+  size_t over_top_size = 0x3000;
+  char *over_top_dup;
+  size_t over_top_dup_size = 0x7000;
+  char *x;
+  size_t i;
+
+  /* Here's what memory is supposed to look like (hex):
+        size  contents
+        3000  original_info_table, later fill_info_table1
+      3fa000  dummy0
+      3fa000  dummy1
+        6000  info_table_2
+	3000  over_top
+
+	*/
+  /* mem: original_info_table */
+  dummy0 = malloc (0x3fa000);
+  /* mem: original_info_table, dummy0 */
+  dummy1 = malloc (0x3fa000);
+  /* mem: free, dummy0, dummy1, info_table_2 */
+  fill_info_table1 = malloc (0x3000);
+  /* mem: fill_info_table1, dummy0, dummy1, info_table_2 */
+
+  x = malloc (0x1000);
+  free (x);
+  /* mem: fill_info_table1, dummy0, dummy1, info_table_2, freexx */
+
+  /* This is what loses; info_table_2 and freexx get combined unbeknownst
+     to mmalloc, and mmalloc puts over_top in a section of memory which
+     is on the free list as part of another block (where info_table_2 had
+     been).  */
+  over_top = malloc (over_top_size);
+  over_top_dup = malloc (over_top_dup_size);
+  memset (over_top, 0, over_top_size);
+  memset (over_top_dup, 1, over_top_dup_size);
+
+  for (i = 0; i < over_top_size; ++i)
+    if (over_top[i] != 0)
+      {
+	printf ("FAIL: malloc expands info table\n");
+	return 0;
+      }
+
+  for (i = 0; i < over_top_dup_size; ++i)
+    if (over_top_dup[i] != 1)
+      {
+	printf ("FAIL: malloc expands info table\n");
+	return 0;
+      }
+
+  printf ("PASS: malloc expands info table\n");
+  return 0;
+}