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b57525f1a3
When "reorder" resolver option is enabled, threads of a multi-threaded process could hang in gethostbyaddr_r, gethostbyname_r, or gethostbyname2_r. Due to a trivial bug in _res_hconf_reorder_addrs, simultaneous invocations of this function in a multi-threaded process could result to _res_hconf_reorder_addrs returning without releasing the lock it holds, causing other threads to block indefinitely while waiting for the lock that is not going to be released. [BZ #17977] * resolv/res_hconf.c (_res_hconf_reorder_addrs): Fix unlocking when initializing interface list, based on the bug analysis and the patch proposed by Eric Newton. * resolv/tst-res_hconf_reorder.c: New test. * resolv/Makefile [$(have-thread-library) = yes] (tests): Add tst-res_hconf_reorder. ($(objpfx)tst-res_hconf_reorder): Depend on $(libdl) and $(shared-thread-library). (tst-res_hconf_reorder-ENV): New variable.
113 lines
2.5 KiB
C
113 lines
2.5 KiB
C
/* BZ #17977 _res_hconf_reorder_addrs test.
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Copyright (C) 2015 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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<http://www.gnu.org/licenses/>. */
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#include <errno.h>
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#include <stdio.h>
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#include <string.h>
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#include <time.h>
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#include <dlfcn.h>
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#include <pthread.h>
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#include <netdb.h>
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#include <netinet/in.h>
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#include <sys/socket.h>
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static struct timespec ts;
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/* The first thread that gets a lock in _res_hconf_reorder_addrs()
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should hold the lock long enough to make two other threads blocked.
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This is achieved by slowing down realloc(3) that is called several times
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by _res_hconf_reorder_addrs(). */
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void *
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realloc (void *ptr, size_t len)
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{
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static void *(*fun) (void *, size_t);
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if (!fun)
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fun = dlsym (RTLD_NEXT, "realloc");
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if (ts.tv_nsec)
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nanosleep (&ts, NULL);
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return (*fun) (ptr, len);
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}
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static void *
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resolve (void *arg)
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{
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struct in_addr addr;
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struct hostent ent;
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struct hostent *result;
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int err;
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char buf[1024];
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addr.s_addr = htonl (INADDR_LOOPBACK);
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(void) gethostbyaddr_r ((void *) &addr, sizeof (addr), AF_INET,
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&ent, buf, sizeof (buf), &result, &err);
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return arg;
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}
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static int
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do_test (void)
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{
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#define N 3
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pthread_t thr[N];
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unsigned int i;
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int result = 0;
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/* turn on realloc slowdown */
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ts.tv_nsec = 100000000;
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for (i = 0; i < N; ++i)
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{
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int rc = pthread_create (&thr[i], NULL, resolve, NULL);
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if (rc)
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{
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printf ("pthread_create: %s\n", strerror(rc));
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exit (1);
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}
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}
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for (i = 0; i < N; ++i)
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{
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void *retval;
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int rc = pthread_join (thr[i], &retval);
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if (rc)
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{
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printf ("pthread_join: %s\n", strerror(rc));
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exit (1);
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}
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if (retval)
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{
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printf ("thread %u exit status %p\n", i, retval);
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result = 1;
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}
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}
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/* turn off realloc slowdown, no longer needed */
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ts.tv_nsec = 0;
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return result;
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}
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#define TEST_FUNCTION do_test ()
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#include "../test-skeleton.c"
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