Commit 2de4e823 authored by Bernd Edlinger's avatar Bernd Edlinger Committed by Eric W. Biederman
Browse files

selftests/ptrace: add test cases for dead-locks 



This adds test cases for ptrace deadlocks.

Additionally fixes a compile problem in get_syscall_info.c,
observed with gcc-4.8.4:

get_syscall_info.c: In function 'get_syscall_info':
get_syscall_info.c:93:3: error: 'for' loop initial declarations are only
                                 allowed in C99 mode
   for (unsigned int i = 0; i < ARRAY_SIZE(args); ++i) {
   ^
get_syscall_info.c:93:3: note: use option -std=c99 or -std=gnu99 to compile
                               your code

Signed-off-by: default avatarBernd Edlinger <bernd.edlinger@hotmail.de>
Reviewed-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarEric W. Biederman <ebiederm@xmission.com>
parent 3e74fabd

tools/testing/selftests/ptrace/Makefile

+2 −2
Original line number Diff line number Diff line 
# SPDX-License-Identifier: GPL-2.0-only

CFLAGS += -iquote../../../../include/uapi -Wall

CFLAGS += -std=c99 -pthread -iquote../../../../include/uapi -Wall



TEST_GEN_PROGS := get_syscall_info peeksiginfo

TEST_GEN_PROGS := get_syscall_info peeksiginfo vmaccess



include ../lib.mk

tools/testing/selftests/ptrace/vmaccess.c

0 → 100644
+86 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0+

/*

 * Copyright (c) 2020 Bernd Edlinger <bernd.edlinger@hotmail.de>

 * All rights reserved.

 *

 * Check whether /proc/$pid/mem can be accessed without causing deadlocks

 * when de_thread is blocked with ->cred_guard_mutex held.

 */



#include "../kselftest_harness.h"

#include <stdio.h>

#include <fcntl.h>

#include <pthread.h>

#include <signal.h>

#include <unistd.h>

#include <sys/ptrace.h>



static void *thread(void *arg)

{

	ptrace(PTRACE_TRACEME, 0, 0L, 0L);

	return NULL;

}



TEST(vmaccess)

{

	int f, pid = fork();

	char mm[64];



	if (!pid) {

		pthread_t pt;



		pthread_create(&pt, NULL, thread, NULL);

		pthread_join(pt, NULL);

		execlp("true", "true", NULL);

	}



	sleep(1);

	sprintf(mm, "/proc/%d/mem", pid);

	f = open(mm, O_RDONLY);

	ASSERT_GE(f, 0);

	close(f);

	f = kill(pid, SIGCONT);

	ASSERT_EQ(f, 0);

}



TEST(attach)

{

	int s, k, pid = fork();



	if (!pid) {

		pthread_t pt;



		pthread_create(&pt, NULL, thread, NULL);

		pthread_join(pt, NULL);

		execlp("sleep", "sleep", "2", NULL);

	}



	sleep(1);

	k = ptrace(PTRACE_ATTACH, pid, 0L, 0L);

	ASSERT_EQ(errno, EAGAIN);

	ASSERT_EQ(k, -1);

	k = waitpid(-1, &s, WNOHANG);

	ASSERT_NE(k, -1);

	ASSERT_NE(k, 0);

	ASSERT_NE(k, pid);

	ASSERT_EQ(WIFEXITED(s), 1);

	ASSERT_EQ(WEXITSTATUS(s), 0);

	sleep(1);

	k = ptrace(PTRACE_ATTACH, pid, 0L, 0L);

	ASSERT_EQ(k, 0);

	k = waitpid(-1, &s, 0);

	ASSERT_EQ(k, pid);

	ASSERT_EQ(WIFSTOPPED(s), 1);

	ASSERT_EQ(WSTOPSIG(s), SIGSTOP);

	k = ptrace(PTRACE_DETACH, pid, 0L, 0L);

	ASSERT_EQ(k, 0);

	k = waitpid(-1, &s, 0);

	ASSERT_EQ(k, pid);

	ASSERT_EQ(WIFEXITED(s), 1);

	ASSERT_EQ(WEXITSTATUS(s), 0);

	k = waitpid(-1, NULL, 0);

	ASSERT_EQ(k, -1);

	ASSERT_EQ(errno, ECHILD);

}



TEST_HARNESS_MAIN