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/*
* libpulp - User-space Livepatching Library
*
* Copyright (C) 2020-2021 SUSE Software Solutions GmbH
*
* This file is part of libpulp.
*
* libpulp 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.
*
* libpulp 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 General Public License
* along with libpulp. If not, see <http://www.gnu.org/licenses/>.
*/
#include <dlfcn.h>
#include <errno.h>
#include <malloc.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
/* At least one thread is required to cause the deadlock, otherwise,
* malloc/calloc refrain from acquiring a lock, at all.
*/
#define THREADS 15
/* A live-patchable library is required so that a live patch can be
* applied, however, this test case only relies on the fact that
* multiple threads in the application use malloc/calloc, not on
* anything specific to libblocked (any live-patchable library could
* have been used).
*/
#include <libblocked.h>
/* Do not optimize, otherwise the calloc/free sequences go away. */
#ifndef __clang__
#pragma GCC push_options
#pragma GCC optimize("O0")
#else
#pragma clang optimize off
#endif
/* Calls many of the functions that acquire the locks that might cause
* live-patch installation to deadlock.
*/
void *
worker(void *arg __attribute__((unused)))
{
void *handle;
void *symbol __attribute__((unused));
char *data;
while (1) {
data = calloc(100, sizeof(char));
data = reallocarray(data, 200, sizeof(char));
free(data);
data = malloc(300 * sizeof(char));
data = realloc(data, 400 * sizeof(char));
free(data);
data = aligned_alloc(256, 500 * sizeof(char));
free(data);
data = valloc(600 * sizeof(char));
free(data);
data = pvalloc(700 * sizeof(char));
free(data);
if (!posix_memalign((void **)&data, 512, 800 * sizeof(char)))
free(data);
handle = dlopen(NULL, RTLD_LAZY | RTLD_NOLOAD);
if (handle != NULL) {
symbol = dlsym(handle, "worker");
dlclose(handle);
}
/* Sleep for a brief while to increase the chances that the
* application of the live-patch succeeds.
*/
usleep(1);
}
}
/* Restore optimization level. */
#ifndef __clang__
#pragma GCC pop_options
#else
#pragma clang optimize on
#endif
int
main(void)
{
char buffer[128];
pthread_t thread[THREADS];
/* Create THREADS threads that try to allocate and free memory in an
* infinite loop.
*/
for (int iter = 0; iter < THREADS; iter++)
pthread_create(&thread[iter], NULL, worker, NULL);
/* Signal readiness. */
printf("Waiting for input.\n");
/* Wait for any input, then call hello(), which should produce
* different output before and after the live-patching.
*/
while (1) {
if (fgets(buffer, sizeof(buffer), stdin) == NULL) {
if (errno) {
perror("deadlock");
return 1;
}
printf("Reached the end of file; quitting.\n");
return 0;
}
hello();
}
return 0;
}
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