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