glibc/nptl/tst-cancel20.c
Adhemerval Zanella d0e3ffb7a5 nptl: Fix racy pipe closing in tst-cancel{20,21}
The tst-cancel20 open two pipes and creates a thread which blocks
reading the first pipe.  It then issues a signal to activate the
signal handler which in turn blocks reading the second pipe end.
Finally the cancellation cleanup-up handlers are tested by first
closing the all the pipes ends and issuing a pthread_cancel.
The tst-cancel21 have a similar behavior, but use an extra fork
after the test itself.

The race condition occurs if the cancellation handling acts after the
pipe close: in this case read will return EOF (indicating side-effects)
and thus the cancellation must not act.  However current GLIBC
cancellation behavior acts regardless the syscalls returns with
sid-effects.

This patch adjust the test by moving the pipe closing after the
cancellation handling.  This avoid spurious cancellation if the case
of the race described.

Checked on x86_64 and i386.

	* nptl/tst-cancel20.c (do_one_test): Move the pipe closing after
	pthread_join.
	* nptl/tst-cancel21.c (tf): Likewise.
2015-12-02 14:45:50 -02:00

269 lines
5.1 KiB
C

/* Copyright (C) 2003-2015 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Jakub Jelinek <jakub@redhat.com>, 2003.
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 <pthread.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
static int fd[4];
static pthread_barrier_t b;
volatile int in_sh_body;
unsigned long cleanups;
static void
cl (void *arg)
{
cleanups = (cleanups << 4) | (long) arg;
}
static void __attribute__((noinline))
sh_body (void)
{
char c;
pthread_cleanup_push (cl, (void *) 1L);
in_sh_body = 1;
if (read (fd[2], &c, 1) == 1)
{
puts ("read succeeded");
exit (1);
}
pthread_cleanup_pop (0);
}
static void
sh (int sig)
{
pthread_cleanup_push (cl, (void *) 2L);
sh_body ();
in_sh_body = 0;
pthread_cleanup_pop (0);
}
static void __attribute__((noinline))
tf_body (void)
{
char c;
pthread_cleanup_push (cl, (void *) 3L);
int r = pthread_barrier_wait (&b);
if (r != 0 && r != PTHREAD_BARRIER_SERIAL_THREAD)
{
puts ("child thread: barrier_wait failed");
exit (1);
}
if (read (fd[0], &c, 1) == 1)
{
puts ("read succeeded");
exit (1);
}
read (fd[0], &c, 1);
pthread_cleanup_pop (0);
}
static void *
tf (void *arg)
{
pthread_cleanup_push (cl, (void *) 4L);
tf_body ();
pthread_cleanup_pop (0);
return NULL;
}
static int
do_one_test (void)
{
in_sh_body = 0;
cleanups = 0;
if (pipe (fd) != 0 || pipe (fd + 2) != 0)
{
puts ("pipe failed");
return 1;
}
pthread_t th;
if (pthread_create (&th, NULL, tf, NULL) != 0)
{
puts ("create failed");
return 1;
}
int r = pthread_barrier_wait (&b);
if (r != 0 && r != PTHREAD_BARRIER_SERIAL_THREAD)
{
puts ("parent thread: barrier_wait failed");
return 1;
}
sleep (1);
r = pthread_kill (th, SIGHUP);
if (r)
{
errno = r;
printf ("pthread_kill failed %m\n");
return 1;
}
while (in_sh_body == 0)
sleep (1);
if (pthread_cancel (th) != 0)
{
puts ("cancel failed");
return 1;
}
void *ret;
if (pthread_join (th, &ret) != 0)
{
puts ("join failed");
return 1;
}
if (ret != PTHREAD_CANCELED)
{
puts ("result is wrong");
return 1;
}
if (cleanups != 0x1234L)
{
printf ("called cleanups %lx\n", cleanups);
return 1;
}
/* The pipe closing must be issued after the cancellation handling to avoid
a race condition where the cancellation runs after both pipe ends are
closed. In this case the read syscall returns EOF and the cancellation
must not act. */
close (fd[0]);
close (fd[1]);
close (fd[2]);
close (fd[3]);
return 0;
}
static int
do_test (void)
{
stack_t ss;
ss.ss_sp = malloc (2 * SIGSTKSZ);
if (ss.ss_sp == NULL)
{
puts ("failed to allocate alternate stack");
return 1;
}
ss.ss_flags = 0;
ss.ss_size = 2 * SIGSTKSZ;
if (sigaltstack (&ss, NULL) < 0)
{
printf ("sigaltstack failed %m\n");
return 1;
}
if (pthread_barrier_init (&b, NULL, 2) != 0)
{
puts ("barrier_init failed");
return 1;
}
struct sigaction sa;
sa.sa_handler = sh;
sigemptyset (&sa.sa_mask);
sa.sa_flags = 0;
if (sigaction (SIGHUP, &sa, NULL) != 0)
{
puts ("sigaction failed");
return 1;
}
puts ("sa_flags = 0 test");
if (do_one_test ())
return 1;
sa.sa_handler = sh;
sigemptyset (&sa.sa_mask);
sa.sa_flags = SA_ONSTACK;
if (sigaction (SIGHUP, &sa, NULL) != 0)
{
puts ("sigaction failed");
return 1;
}
puts ("sa_flags = SA_ONSTACK test");
if (do_one_test ())
return 1;
#ifdef SA_SIGINFO
sa.sa_sigaction = (void (*)(int, siginfo_t *, void *)) sh;
sigemptyset (&sa.sa_mask);
sa.sa_flags = SA_SIGINFO;
if (sigaction (SIGHUP, &sa, NULL) != 0)
{
puts ("sigaction failed");
return 1;
}
puts ("sa_flags = SA_SIGINFO test");
if (do_one_test ())
return 1;
sa.sa_sigaction = (void (*)(int, siginfo_t *, void *)) sh;
sigemptyset (&sa.sa_mask);
sa.sa_flags = SA_SIGINFO | SA_ONSTACK;
if (sigaction (SIGHUP, &sa, NULL) != 0)
{
puts ("sigaction failed");
return 1;
}
puts ("sa_flags = SA_SIGINFO|SA_ONSTACK test");
if (do_one_test ())
return 1;
#endif
return 0;
}
#define TIMEOUT 40
#define TEST_FUNCTION do_test ()
#include "../test-skeleton.c"