[PATCH 2/4] selftests/ptrace: add test cases for dead-locks
From: Bernd Edlinger <hidden>
Date: 2020-03-10 13:44:38
Also in:
linux-doc, linux-fsdevel, linux-mm, lkml, stable
Subsystem:
kernel selftest framework, the rest · Maintainers:
Shuah Khan, Linus Torvalds
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: Bernd Edlinger <redacted>
---
tools/testing/selftests/ptrace/Makefile | 4 +-
tools/testing/selftests/ptrace/vmaccess.c | 86 +++++++++++++++++++++++++++++++
2 files changed, 88 insertions(+), 2 deletions(-)
create mode 100644 tools/testing/selftests/ptrace/vmaccess.c
diff --git a/tools/testing/selftests/ptrace/Makefile b/tools/testing/selftests/ptrace/Makefile
index c0b7f89..2f1f532 100644
--- a/tools/testing/selftests/ptrace/Makefile
+++ b/tools/testing/selftests/ptrace/Makefile@@ -1,6 +1,6 @@ # 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
diff --git a/tools/testing/selftests/ptrace/vmaccess.c b/tools/testing/selftests/ptrace/vmaccess.c
new file mode 100644
index 0000000..4db327b
--- /dev/null
+++ b/tools/testing/selftests/ptrace/vmaccess.c@@ -0,0 +1,86 @@ +// 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
--
1.9.1