i386: In makecontext, align the stack before calling exit [BZ #22667]

Before this change, if glibc was compiled with SSE instructions and a
sufficiently recent GCC, an unaligned stack access in
__run_exit_handlers would cause stdlib/tst-makecontext to crash.
This commit is contained in:
Florian Weimer 2018-01-04 18:00:05 +01:00
parent 82eef55f8f
commit 8a5df95ffa
4 changed files with 263 additions and 3 deletions

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@ -1,3 +1,11 @@
2018-01-04 Florian Weimer <fweimer@redhat.com>
[BZ #22667]
* sysdeps/unix/sysv/linux/i386/makecontext.S (__makecontext):
Align the stack before calling exit.
* stdlib/tst-makecontext-align.c: New file.
* stdlib/Makefile (tests): Add tst-makecontext-align.
2018-01-04 Florian Weimer <fweimer@redhat.com>
Add support for calling dlvsym from libc.so.

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@ -83,7 +83,8 @@ tests := tst-strtol tst-strtod testmb testrand testsort testdiv \
tst-getrandom tst-atexit tst-at_quick_exit \
tst-cxa_atexit tst-on_exit test-atexit-race \
test-at_quick_exit-race test-cxa_atexit-race \
test-on_exit-race test-dlclose-exit-race
test-on_exit-race test-dlclose-exit-race \
tst-makecontext-align
tests-internal := tst-strtod1i tst-strtod3 tst-strtod4 tst-strtod5i \
tst-tls-atexit tst-tls-atexit-nodelete

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@ -0,0 +1,241 @@
/* Check stack alignment provided by makecontext.
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 <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <support/check.h>
#include <support/namespace.h>
#include <support/xunistd.h>
#include <sys/mman.h>
#include <ucontext.h>
/* Used for error reporting. */
static const char *context;
/* Check that ADDRESS is aligned to ALIGNMENT bytes, behind a compiler
barrier. */
__attribute__ ((noinline, noclone, weak))
void
check_align (void *address, size_t alignment)
{
uintptr_t uaddress = (uintptr_t) address;
if ((uaddress % alignment) != 0)
{
support_record_failure ();
printf ("error: %s: object at address %p is not aligned to %zu bytes\n",
context, address, alignment);
}
}
/* Various alignment checking functions. */
__attribute__ ((noinline, noclone, weak))
void
check_align_int (void)
{
int a;
check_align (&a, __alignof__ (a));
}
__attribute__ ((noinline, noclone, weak))
void
check_align_long (void)
{
long a;
check_align (&a, __alignof__ (a));
}
__attribute__ ((noinline, noclone, weak))
void
check_align_long_long (void)
{
long long a;
check_align (&a, __alignof__ (a));
}
__attribute__ ((noinline, noclone, weak))
void
check_align_double (void)
{
double a;
check_align (&a, __alignof__ (a));
}
__attribute__ ((noinline, noclone, weak))
void
check_align_4 (void)
{
int a __attribute__ ((aligned (4)));
check_align (&a, 4);
}
__attribute__ ((noinline, noclone, weak))
void
check_align_8 (void)
{
double a __attribute__ ((aligned (8)));
check_align (&a, 8);
}
__attribute__ ((noinline, noclone, weak))
void
check_align_16 (void)
{
struct aligned
{
double x0 __attribute__ ((aligned (16)));
double x1;
} a;
check_align (&a, 16);
}
__attribute__ ((noinline, noclone, weak))
void
check_align_32 (void)
{
struct aligned
{
double x0 __attribute__ ((aligned (32)));
double x1;
double x2;
double x3;
} a;
check_align (&a, 32);
}
/* Call all the alignment checking functions. */
__attribute__ ((noinline, noclone, weak))
void
check_alignments (void)
{
check_align_int ();
check_align_long ();
check_align_long_long ();
check_align_double ();
check_align_4 ();
check_align_8 ();
check_align_16 ();
check_align_32 ();
}
/* Callback functions for makecontext and their invokers (to be used
with support_isolate_in_subprocess). */
static ucontext_t ucp;
static void
callback_0 (void)
{
context = "callback_0";
check_alignments ();
context = "after return from callback_0";
}
static void
invoke_callback_0 (void *closure)
{
makecontext (&ucp, (void *) callback_0, 0);
if (setcontext (&ucp) != 0)
FAIL_EXIT1 ("setcontext");
FAIL_EXIT1 ("setcontext returned");
}
static void
callback_1 (int arg1)
{
context = "callback_1";
check_alignments ();
TEST_COMPARE (arg1, 101);
context = "after return from callback_1";
}
static void
invoke_callback_1 (void *closure)
{
makecontext (&ucp, (void *) callback_1, 1, 101);
if (setcontext (&ucp) != 0)
FAIL_EXIT1 ("setcontext");
FAIL_EXIT1 ("setcontext returned");
}
static void
callback_2 (int arg1, int arg2)
{
context = "callback_2";
check_alignments ();
TEST_COMPARE (arg1, 201);
TEST_COMPARE (arg2, 202);
context = "after return from callback_2";
}
static void
invoke_callback_2 (void *closure)
{
makecontext (&ucp, (void *) callback_2, 2, 201, 202);
if (setcontext (&ucp) != 0)
FAIL_EXIT1 ("setcontext");
FAIL_EXIT1 ("setcontext returned");
}
static void
callback_3 (int arg1, int arg2, int arg3)
{
context = "callback_3";
check_alignments ();
TEST_COMPARE (arg1, 301);
TEST_COMPARE (arg2, 302);
TEST_COMPARE (arg3, 303);
context = "after return from callback_3";
}
static void
invoke_callback_3 (void *closure)
{
makecontext (&ucp, (void *) callback_3, 3, 301, 302, 303);
if (setcontext (&ucp) != 0)
FAIL_EXIT1 ("setcontext");
FAIL_EXIT1 ("setcontext returned");
}
static int
do_test (void)
{
context = "direct call";
check_alignments ();
atexit (check_alignments);
if (getcontext (&ucp) != 0)
FAIL_UNSUPPORTED ("getcontext");
ucp.uc_link = NULL;
ucp.uc_stack.ss_size = 512 * 1024;
ucp.uc_stack.ss_sp = xmmap (NULL, ucp.uc_stack.ss_size,
PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS, -1);
support_isolate_in_subprocess (invoke_callback_0, NULL);
support_isolate_in_subprocess (invoke_callback_1, NULL);
support_isolate_in_subprocess (invoke_callback_2, NULL);
support_isolate_in_subprocess (invoke_callback_3, NULL);
return 0;
}
#include <support/test-driver.c>

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@ -108,9 +108,19 @@ L(exitcode):
call HIDDEN_JUMPTARGET(__setcontext)
/* If this returns (which can happen if the syscall fails) we'll
exit the program with the return error value (-1). */
jmp L(call_exit)
movl %eax, (%esp)
2: call HIDDEN_JUMPTARGET(exit)
2:
/* Exit with status 0. */
xorl %eax, %eax
L(call_exit):
/* Align the stack and pass the exit code (from %eax). */
andl $0xfffffff0, %esp
subl $12, %esp
pushl %eax
call HIDDEN_JUMPTARGET(exit)
/* The 'exit' call should never return. In case it does cause
the process to terminate. */
hlt