malloc: tcache double free check

* malloc/malloc.c (tcache_entry): Add key field.
(tcache_put): Set it.
(tcache_get): Likewise.
(_int_free): Check for double free in tcache.
* malloc/tst-tcfree1.c: New.
* malloc/tst-tcfree2.c: New.
* malloc/Makefile: Run the new tests.
* manual/probes.texi: Document memory_tcache_double_free probe.

* dlfcn/dlerror.c (check_free): Prevent double frees.

1 files changed, 42 insertions, 0 deletions

diff --git a/malloc/tst-tcfree1.c b/malloc/tst-tcfree1.c
new file mode 100644
index 0000000..bc29375
--- /dev/null
+++ b/malloc/tst-tcfree1.c
@@ -0,0 +1,42 @@
+/* Test that malloc tcache catches double free.
+   Copyright (C) 2018 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
+   <http://www.gnu.org/licenses/>.  */
+
+#include <errno.h>
+#include <error.h>
+#include <limits.h>
+#include <malloc.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <sys/signal.h>
+
+static int
+do_test (void)
+{
+  /* Do one allocation of any size that fits in tcache.  */
+  char * volatile x = malloc (32);
+
+  free (x); // puts in tcache
+  free (x); // should abort
+
+  printf("FAIL: tcache double free not detected\n");
+  return 1;
+}
+
+#define TEST_FUNCTION do_test
+#define EXPECTED_SIGNAL SIGABRT
+#include <support/test-driver.c>