LXR linux/tools/testing/selftests/ptrace/vmaccess.c

   1// SPDX-License-Identifier: GPL-2.0+
   2/*
   3 * Copyright (c) 2020 Bernd Edlinger <bernd.edlinger@hotmail.de>
   4 * All rights reserved.
   5 *
   6 * Check whether /proc/$pid/mem can be accessed without causing deadlocks
   7 * when de_thread is blocked with ->cred_guard_mutex held.
   8 */
   9
  10#include "../kselftest_harness.h"
  11#include <stdio.h>
  12#include <fcntl.h>
  13#include <pthread.h>
  14#include <signal.h>
  15#include <unistd.h>
  16#include <sys/ptrace.h>
  17
  18static void *thread(void *arg)
  19{
  20        ptrace(PTRACE_TRACEME, 0, 0L, 0L);
  21        return NULL;
  22}
  23
  24TEST(vmaccess)
  25{
  26        int f, pid = fork();
  27        char mm[64];
  28
  29        if (!pid) {
  30                pthread_t pt;
  31
  32                pthread_create(&pt, NULL, thread, NULL);
  33                pthread_join(pt, NULL);
  34                execlp("true", "true", NULL);
  35        }
  36
  37        sleep(1);
  38        sprintf(mm, "/proc/%d/mem", pid);
  39        f = open(mm, O_RDONLY);
  40        ASSERT_GE(f, 0);
  41        close(f);
  42        f = kill(pid, SIGCONT);
  43        ASSERT_EQ(f, 0);
  44}
  45
  46TEST(attach)
  47{
  48        int s, k, pid = fork();
  49
  50        if (!pid) {
  51                pthread_t pt;
  52
  53                pthread_create(&pt, NULL, thread, NULL);
  54                pthread_join(pt, NULL);
  55                execlp("sleep", "sleep", "2", NULL);
  56        }
  57
  58        sleep(1);
  59        k = ptrace(PTRACE_ATTACH, pid, 0L, 0L);
  60        ASSERT_EQ(errno, EAGAIN);
  61        ASSERT_EQ(k, -1);
  62        k = waitpid(-1, &s, WNOHANG);
  63        ASSERT_NE(k, -1);
  64        ASSERT_NE(k, 0);
  65        ASSERT_NE(k, pid);
  66        ASSERT_EQ(WIFEXITED(s), 1);
  67        ASSERT_EQ(WEXITSTATUS(s), 0);
  68        sleep(1);
  69        k = ptrace(PTRACE_ATTACH, pid, 0L, 0L);
  70        ASSERT_EQ(k, 0);
  71        k = waitpid(-1, &s, 0);
  72        ASSERT_EQ(k, pid);
  73        ASSERT_EQ(WIFSTOPPED(s), 1);
  74        ASSERT_EQ(WSTOPSIG(s), SIGSTOP);
  75        k = ptrace(PTRACE_DETACH, pid, 0L, 0L);
  76        ASSERT_EQ(k, 0);
  77        k = waitpid(-1, &s, 0);
  78        ASSERT_EQ(k, pid);
  79        ASSERT_EQ(WIFEXITED(s), 1);
  80        ASSERT_EQ(WEXITSTATUS(s), 0);
  81        k = waitpid(-1, NULL, 0);
  82        ASSERT_EQ(k, -1);
  83        ASSERT_EQ(errno, ECHILD);
  84}
  85
  86TEST_HARNESS_MAIN
  87