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

source code of linux/tools/testing/selftests/ptrace/vmaccess.c