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/* Test reporting of Safe-Linking caught errors.
Copyright (C) 2020-2026 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 <signal.h>
#include <stdint.h>
#include <stdlib.h>
#include <memory.h>
#include <string.h>
#include <time.h>
#include <stdbool.h>
#include <support/capture_subprocess.h>
#include <support/check.h>
#include "tst-malloc-aux.h"
/* Run CALLBACK and check that the data on standard error equals
EXPECTED. */
static void
check (const char *test, void (*callback) (void *),
const char *expected)
{
int i, rand_mask;
int success = 0; /* 0 == fail, 1 == other check 2 == safe linking */
/* There is a chance of 1/16 that a corrupted pointer will be aligned.
Try multiple times so that statistical failure will be improbable. */
for (i = 0; i < 16; ++i)
{
rand_mask = rand () & 0xFF;
struct support_capture_subprocess result
= support_capture_subprocess (callback, &rand_mask);
printf ("%s\n", result.out.buffer);
/* Did not crash, could happen. Try again. */
if (strlen (result.err.buffer) == 0)
continue;
/* Crashed, it may either be safe linking or some other check. If it's
not safe linking then try again. */
if (strcmp (result.err.buffer, expected) != 0)
{
printf ("test %s failed with a different error\n"
" expected: %s\n"
" actual: %s\n",
test, expected, result.err.buffer);
success = 1;
continue;
}
TEST_VERIFY (WIFSIGNALED (result.status));
if (WIFSIGNALED (result.status))
TEST_VERIFY (WTERMSIG (result.status) == SIGABRT);
support_capture_subprocess_free (&result);
success = 2;
break;
}
/* The test fails only if the corruption was not caught by any of the malloc
mechanisms in all those iterations. This has a lower than 1 in 2^64
chance of a false positive. */
TEST_VERIFY (success);
}
/* Implementation details must be kept in sync with malloc. */
#define TCACHE_FILL_COUNT 7
#define TCACHE_ALLOC_SIZE 0x20
/* Try corrupting the tcache list. */
static void
test_tcache (void *closure)
{
int mask = ((int *)closure)[0];
size_t size = TCACHE_ALLOC_SIZE;
printf ("++ tcache ++\n");
/* Populate the tcache list. */
void * volatile a = malloc (size);
void * volatile b = malloc (size);
void * volatile c = malloc (size);
printf ("a=%p, b=%p, c=%p\n", a, b, c);
free (a);
free (b);
free (c);
/* Corrupt the pointer with a random value, and avoid optimizations. */
printf ("Before: c=%p, c[0]=%p\n", c, ((void **)c)[0]);
memset (c, mask & 0xFF, size);
printf ("After: c=%p, c[0]=%p\n", c, ((void **)c)[0]);
c = malloc (size);
printf ("Allocated: c=%p\n", c);
/* This line will trigger the Safe-Linking check. */
b = malloc (size);
printf ("b=%p\n", b);
}
static int
do_test (void)
{
/* Seed the random for the test. */
srand (time (NULL));
check ("test_tcache", test_tcache,
"malloc(): unaligned tcache chunk detected\n");
return 0;
}
#include <support/test-driver.c>
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