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d40ac01cbb
The recursive lock used on abort does not synchronize with a new process
creation (either by fork-like interfaces or posix_spawn ones), nor it
is reinitialized after fork().
Also, the SIGABRT unblock before raise() shows another race condition,
where a fork or posix_spawn() call by another thread, just after the
recursive lock release and before the SIGABRT signal, might create
programs with a non-expected signal mask. With the default option
(without POSIX_SPAWN_SETSIGDEF), the process can see SIG_DFL for
SIGABRT, where it should be SIG_IGN.
To fix the AS-safe, raise() does not change the process signal mask,
and an AS-safe lock is used if a SIGABRT is installed or the process
is blocked or ignored. With the signal mask change removal,
there is no need to use a recursive loc. The lock is also taken on
both _Fork() and posix_spawn(), to avoid the spawn process to see the
abort handler as SIG_DFL.
A read-write lock is used to avoid serialize _Fork and posix_spawn
execution. Both sigaction (SIGABRT) and abort() requires to lock
as writer (since both change the disposition).
The fallback is also simplified: there is no need to use a loop of
ABORT_INSTRUCTION after _exit() (if the syscall does not terminate the
process, the system is broken).
The proposed fix changes how setjmp works on a SIGABRT handler, where
glibc does not save the signal mask. So usage like the below will now
always abort.
static volatile int chk_fail_ok;
static jmp_buf chk_fail_buf;
static void
handler (int sig)
{
if (chk_fail_ok)
{
chk_fail_ok = 0;
longjmp (chk_fail_buf, 1);
}
else
_exit (127);
}
[...]
signal (SIGABRT, handler);
[....]
chk_fail_ok = 1;
if (! setjmp (chk_fail_buf))
{
// Something that can calls abort, like a failed fortify function.
chk_fail_ok = 0;
printf ("FAIL\n");
}
Such cases will need to use sigsetjmp instead.
The _dl_start_profile calls sigaction through _profil, and to avoid
pulling abort() on loader the call is replaced with __libc_sigaction.
Checked on x86_64-linux-gnu and aarch64-linux-gnu.
Reviewed-by: DJ Delorie <dj@redhat.com>
356 lines
8.0 KiB
C
356 lines
8.0 KiB
C
/* Test and measure __strcpy_chk functions.
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Copyright (C) 1999-2024 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#ifndef STRCPY_RESULT
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# define STRCPY_RESULT(dst, len) dst
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# define TEST_MAIN
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# define TEST_NAME "strcpy_chk"
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# include <string/test-string.h>
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/* This test case implicitly tests the availability of the __chk_fail
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symbol, which is part of the public ABI and may be used
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externally. */
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extern void __attribute__ ((noreturn)) __chk_fail (void);
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char *simple_strcpy_chk (char *, const char *, size_t);
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extern char *normal_strcpy (char *, const char *, size_t)
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__asm ("strcpy");
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extern char *__strcpy_chk (char *, const char *, size_t);
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IMPL (simple_strcpy_chk, 0)
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IMPL (normal_strcpy, 1)
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IMPL (__strcpy_chk, 2)
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char *
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simple_strcpy_chk (char *dst, const char *src, size_t len)
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{
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char *ret = dst;
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if (! len)
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__chk_fail ();
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while ((*dst++ = *src++) != '\0')
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if (--len == 0)
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__chk_fail ();
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return ret;
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}
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#endif
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#include <fcntl.h>
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#include <paths.h>
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#include <setjmp.h>
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#include <signal.h>
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static int test_main (void);
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#define TEST_FUNCTION test_main
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#include <support/test-driver.c>
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#include <support/support.h>
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volatile int chk_fail_ok;
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sigjmp_buf chk_fail_buf;
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static void
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handler (int sig)
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{
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if (chk_fail_ok)
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{
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chk_fail_ok = 0;
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longjmp (chk_fail_buf, 1);
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}
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else
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_exit (127);
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}
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typedef char *(*proto_t) (char *, const char *, size_t);
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static void
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do_one_test (impl_t *impl, char *dst, const char *src,
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size_t len, size_t dlen)
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{
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char *res;
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if (dlen <= len)
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{
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if (impl->test == 1)
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return;
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chk_fail_ok = 1;
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if (sigsetjmp (chk_fail_buf, 1) == 0)
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{
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res = CALL (impl, dst, src, dlen);
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printf ("*** Function %s (%zd; %zd) did not __chk_fail\n",
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impl->name, len, dlen);
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chk_fail_ok = 0;
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ret = 1;
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}
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return;
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}
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else
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res = CALL (impl, dst, src, dlen);
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if (res != STRCPY_RESULT (dst, len))
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{
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printf ("Wrong result in function %s %p %p\n", impl->name,
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res, STRCPY_RESULT (dst, len));
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ret = 1;
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return;
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}
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if (strcmp (dst, src) != 0)
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{
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printf ("Wrong result in function %s dst \"%s\" src \"%s\"\n",
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impl->name, dst, src);
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ret = 1;
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return;
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}
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}
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static void
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do_test (size_t align1, size_t align2, size_t len, size_t dlen, int max_char)
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{
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size_t i;
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char *s1, *s2;
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align1 &= 7;
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if (align1 + len >= page_size)
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return;
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align2 &= 7;
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if (align2 + len >= page_size)
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return;
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s1 = (char *) buf1 + align1;
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s2 = (char *) buf2 + align2;
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for (i = 0; i < len; i++)
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s1[i] = 32 + 23 * i % (max_char - 32);
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s1[len] = 0;
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FOR_EACH_IMPL (impl, 0)
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do_one_test (impl, s2, s1, len, dlen);
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}
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static void
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do_random_tests (void)
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{
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size_t i, j, n, align1, align2, len, dlen;
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unsigned char *p1 = buf1 + page_size - 512;
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unsigned char *p2 = buf2 + page_size - 512;
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unsigned char *res;
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for (n = 0; n < ITERATIONS; n++)
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{
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align1 = random () & 31;
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if (random () & 1)
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align2 = random () & 31;
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else
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align2 = align1 + (random () & 24);
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len = random () & 511;
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j = align1;
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if (align2 > j)
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j = align2;
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if (len + j >= 511)
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len = 510 - j - (random () & 7);
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j = len + align1 + 64;
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if (j > 512)
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j = 512;
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for (i = 0; i < j; i++)
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{
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if (i == len + align1)
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p1[i] = 0;
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else
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{
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p1[i] = random () & 255;
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if (i >= align1 && i < len + align1 && !p1[i])
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p1[i] = (random () & 127) + 3;
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}
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}
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switch (random () & 7)
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{
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case 0:
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dlen = len - (random () & 31);
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if (dlen > len)
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dlen = len;
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break;
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case 1:
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dlen = (size_t) -1;
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break;
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case 2:
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dlen = len + 1 + (random () & 65535);
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break;
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case 3:
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dlen = len + 1 + (random () & 255);
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break;
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case 4:
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dlen = len + 1 + (random () & 31);
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break;
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case 5:
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dlen = len + 1 + (random () & 7);
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break;
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case 6:
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dlen = len + 1 + (random () & 3);
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break;
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default:
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dlen = len + 1;
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break;
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}
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FOR_EACH_IMPL (impl, 1)
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{
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if (dlen <= len)
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{
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if (impl->test != 1)
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{
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chk_fail_ok = 1;
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if (sigsetjmp (chk_fail_buf, 1) == 0)
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{
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res = (unsigned char *)
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CALL (impl, (char *) p2 + align2,
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(char *) p1 + align1, dlen);
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printf ("Iteration %zd - did not __chk_fail\n", n);
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chk_fail_ok = 0;
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ret = 1;
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}
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}
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continue;
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}
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memset (p2 - 64, '\1', 512 + 64);
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res = (unsigned char *)
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CALL (impl, (char *) p2 + align2, (char *) p1 + align1, dlen);
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if (res != STRCPY_RESULT (p2 + align2, len))
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{
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printf ("\
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Iteration %zd - wrong result in function %s (%zd, %zd, %zd) %p != %p\n",
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n, impl->name, align1, align2, len, res,
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STRCPY_RESULT (p2 + align2, len));
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ret = 1;
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}
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for (j = 0; j < align2 + 64; ++j)
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{
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if (p2[j - 64] != '\1')
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{
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printf ("\
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Iteration %zd - garbage before, %s (%zd, %zd, %zd)\n",
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n, impl->name, align1, align2, len);
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ret = 1;
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break;
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}
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}
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for (j = align2 + len + 1; j < 512; ++j)
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{
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if (p2[j] != '\1')
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{
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printf ("\
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Iteration %zd - garbage after, %s (%zd, %zd, %zd)\n",
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n, impl->name, align1, align2, len);
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ret = 1;
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break;
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}
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}
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if (memcmp (p1 + align1, p2 + align2, len + 1))
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{
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printf ("\
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Iteration %zd - different strings, %s (%zd, %zd, %zd)\n",
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n, impl->name, align1, align2, len);
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ret = 1;
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}
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}
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}
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}
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static int
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test_main (void)
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{
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size_t i;
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set_fortify_handler (handler);
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test_init ();
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printf ("%23s", "");
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FOR_EACH_IMPL (impl, 0)
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printf ("\t%s", impl->name);
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putchar ('\n');
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for (i = 0; i < 16; ++i)
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{
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do_test (0, 0, i, i + 1, 127);
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do_test (0, 0, i, i + 1, 255);
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do_test (0, i, i, i + 1, 127);
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do_test (i, 0, i, i + 1, 255);
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}
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for (i = 1; i < 8; ++i)
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{
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do_test (0, 0, 8 << i, (8 << i) + 1, 127);
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do_test (8 - i, 2 * i, (8 << i), (8 << i) + 1, 127);
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}
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for (i = 1; i < 8; ++i)
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{
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do_test (i, 2 * i, (8 << i), (8 << i) + 1, 127);
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do_test (2 * i, i, (8 << i), (8 << i) + 1, 255);
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do_test (i, i, (8 << i), (8 << i) + 1, 127);
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do_test (i, i, (8 << i), (8 << i) + 1, 255);
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}
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for (i = 0; i < 16; ++i)
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{
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do_test (0, 0, i, i + 256, 127);
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do_test (0, 0, i, i + 256, 255);
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do_test (0, i, i, i + 256, 127);
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do_test (i, 0, i, i + 256, 255);
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}
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for (i = 1; i < 8; ++i)
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{
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do_test (0, 0, 8 << i, (8 << i) + 256, 127);
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do_test (8 - i, 2 * i, (8 << i), (8 << i) + 256, 127);
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}
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for (i = 1; i < 8; ++i)
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{
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do_test (i, 2 * i, (8 << i), (8 << i) + 256, 127);
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do_test (2 * i, i, (8 << i), (8 << i) + 256, 255);
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do_test (i, i, (8 << i), (8 << i) + 256, 127);
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do_test (i, i, (8 << i), (8 << i) + 256, 255);
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}
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for (i = 0; i < 16; ++i)
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{
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do_test (0, 0, i, i, 127);
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do_test (0, 0, i, i + 2, 255);
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do_test (0, i, i, i + 3, 127);
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do_test (i, 0, i, i + 4, 255);
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}
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for (i = 1; i < 8; ++i)
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{
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do_test (0, 0, 8 << i, (8 << i) - 15, 127);
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do_test (8 - i, 2 * i, (8 << i), (8 << i) + 5, 127);
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}
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for (i = 1; i < 8; ++i)
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{
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do_test (i, 2 * i, (8 << i), (8 << i) + i, 127);
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do_test (2 * i, i, (8 << i), (8 << i) + (i - 1), 255);
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do_test (i, i, (8 << i), (8 << i) + i + 2, 127);
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do_test (i, i, (8 << i), (8 << i) + i + 3, 255);
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}
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do_random_tests ();
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return ret;
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}
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