1 files changed, 59 insertions, 0 deletions
diff --git a/malloc/tst-tcfree4.c b/malloc/tst-tcfree4.c
new file mode 100644
index 0000000..03850dd
--- /dev/null
+++ b/malloc/tst-tcfree4.c
@@ -0,0 +1,59 @@
+/* Test that malloc tcache catches double free.
+   Copyright (C) 2025 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <errno.h>
+#include <error.h>
+#include <limits.h>
+#include <malloc.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/signal.h>
+
+/* Test for a double free where the size information gets overwritten by a
+ * terminating null byte.  */
+static int
+do_test (void)
+{
+  /* The payload is exactly 0x19 Bytes long:
+   * 0x18 bytes 'B' and one terminating null byte
+   */
+  const char *payload = "BBBBBBBBBBBBBBBBBBBBBBBB";
+
+  char *volatile first_chunk
+      = malloc (strlen (payload)); // <-- off by one error
+  char *volatile second_chunk = malloc (0x118);
+
+  // free the second chunk the first time now it is in the tcache with tc_idx =
+  free (second_chunk);
+
+  // change the the size of the second_chunk using the terminating null byte if
+  // the PAYLOAD
+  strcpy (first_chunk, payload);
+
+  // now the second_chunk has a new size
+  // calling free a second time will not trigger the double free detection
+  free (second_chunk);
+
+  printf ("FAIL: tcache double free not detected\n");
+  return 1;
+}
+
+#define TEST_FUNCTION do_test
+#define EXPECTED_SIGNAL SIGABRT
+#include <support/test-driver.c>