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
  18 static void *thread(void *arg)
  19 {
  20         ptrace(PTRACE_TRACEME, 0, 0L, 0L);
  21         return NULL;
  22 }
  23
  24 TEST(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
  46 TEST(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
  86 TEST_HARNESS_MAIN