Passing a stack-local child_pid to clone() with CLONE_CHILD_CLEARTID is unsafe: the kernel clears that address when the child exits, which may happen after the test function has returned and the stack slot has been reused.
Neither testcase uses the settid/cleartid pointers for synchronization. Drop CLONE_PARENT_SETTID and CLONE_CHILD_CLEARTID and pass NULL for the clone tid arguments. Wait for the clone child to exit via tkill in test_sigsegv_handler_with_different_pkey_for_stack(), matching test_pkru_sigreturn(), so the detached thread cannot overlap with the next testcase. Signed-off-by: Hongfu Li <[email protected]> --- .../selftests/mm/pkey_sighandler_tests.c | 20 +++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) diff --git a/tools/testing/selftests/mm/pkey_sighandler_tests.c b/tools/testing/selftests/mm/pkey_sighandler_tests.c index cbc24d6cf770..c218d0510a2a 100644 --- a/tools/testing/selftests/mm/pkey_sighandler_tests.c +++ b/tools/testing/selftests/mm/pkey_sighandler_tests.c @@ -290,7 +290,6 @@ static void test_sigsegv_handler_with_different_pkey_for_stack(void) static stack_t sigstack; void *stack; int pkey; - int parent_pid = 0; int child_pid = 0; u64 pkey_reg; long ret; @@ -330,11 +329,10 @@ static void test_sigsegv_handler_with_different_pkey_for_stack(void) /* Use clone to avoid newer glibcs using rseq on new threads */ ret = clone_raw(CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND | CLONE_THREAD | CLONE_SYSVSEM | - CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID | CLONE_DETACHED, stack + STACK_SIZE, - &parent_pid, - &child_pid); + NULL, + NULL); if (ret < 0) { errno = -ret; @@ -344,11 +342,19 @@ static void test_sigsegv_handler_with_different_pkey_for_stack(void) syscall_raw(SYS_exit, 0, 0, 0, 0, 0, 0); } + child_pid = ret; + pthread_mutex_lock(&mutex); while (siginfo.si_signo == 0) pthread_cond_wait(&cond, &mutex); pthread_mutex_unlock(&mutex); + /* Wait for child to exit before returning */ + do { + sched_yield(); + ret = syscall_raw(SYS_tkill, child_pid, 0, 0, 0, 0, 0); + } while (ret != -ESRCH && ret != -EINVAL); + ksft_test_result(siginfo.si_signo == SIGSEGV && siginfo.si_code == SEGV_MAPERR && siginfo.si_addr == NULL, @@ -445,7 +451,6 @@ static void test_pkru_sigreturn(void) static stack_t sigstack; void *stack; int pkey; - int parent_pid = 0; int child_pid = 0; u64 pkey_reg; long ret; @@ -504,11 +509,10 @@ static void test_pkru_sigreturn(void) /* Use clone to avoid newer glibcs using rseq on new threads */ ret = clone_raw(CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND | CLONE_THREAD | CLONE_SYSVSEM | - CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID | CLONE_DETACHED, stack + STACK_SIZE, - &parent_pid, - &child_pid); + NULL, + NULL); if (ret < 0) { errno = -ret; -- 2.25.1
