linux/tools/testing/selftests/x86/vdso_restorer.c
Andy Lutomirski 07f24dc95d selftests/x86/vdso: Fix no-vDSO segfaults
test_vdso would try to call a NULL pointer if the vDSO was missing.

vdso_restorer_32 hit a genuine failure: trying to use the
kernel-provided signal restorer doesn't work if the vDSO is missing.
Skip the test if the vDSO is missing, since the test adds no particular
value in that case.

Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/618ea7b8c55b10d08b1cb139e9a3a957934b8647.1584653439.git.luto@kernel.org
2020-03-20 11:20:04 +01:00

96 lines
2.2 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* vdso_restorer.c - tests vDSO-based signal restore
* Copyright (c) 2015 Andrew Lutomirski
*
* This makes sure that sa_restorer == NULL keeps working on 32-bit
* configurations. Modern glibc doesn't use it under any circumstances,
* so it's easy to overlook breakage.
*
* 64-bit userspace has never supported sa_restorer == NULL, so this is
* 32-bit only.
*/
#define _GNU_SOURCE
#include <err.h>
#include <stdio.h>
#include <dlfcn.h>
#include <string.h>
#include <signal.h>
#include <unistd.h>
#include <syscall.h>
#include <sys/syscall.h>
/* Open-code this -- the headers are too messy to easily use them. */
struct real_sigaction {
void *handler;
unsigned long flags;
void *restorer;
unsigned int mask[2];
};
static volatile sig_atomic_t handler_called;
static void handler_with_siginfo(int sig, siginfo_t *info, void *ctx_void)
{
handler_called = 1;
}
static void handler_without_siginfo(int sig)
{
handler_called = 1;
}
int main()
{
int nerrs = 0;
struct real_sigaction sa;
void *vdso = dlopen("linux-vdso.so.1",
RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
if (!vdso)
vdso = dlopen("linux-gate.so.1",
RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
if (!vdso) {
printf("[SKIP]\tFailed to find vDSO. Tests are not expected to work.\n");
return 0;
}
memset(&sa, 0, sizeof(sa));
sa.handler = handler_with_siginfo;
sa.flags = SA_SIGINFO;
sa.restorer = NULL; /* request kernel-provided restorer */
printf("[RUN]\tRaise a signal, SA_SIGINFO, sa.restorer == NULL\n");
if (syscall(SYS_rt_sigaction, SIGUSR1, &sa, NULL, 8) != 0)
err(1, "raw rt_sigaction syscall");
raise(SIGUSR1);
if (handler_called) {
printf("[OK]\tSA_SIGINFO handler returned successfully\n");
} else {
printf("[FAIL]\tSA_SIGINFO handler was not called\n");
nerrs++;
}
printf("[RUN]\tRaise a signal, !SA_SIGINFO, sa.restorer == NULL\n");
sa.flags = 0;
sa.handler = handler_without_siginfo;
if (syscall(SYS_sigaction, SIGUSR1, &sa, 0) != 0)
err(1, "raw sigaction syscall");
handler_called = 0;
raise(SIGUSR1);
if (handler_called) {
printf("[OK]\t!SA_SIGINFO handler returned successfully\n");
} else {
printf("[FAIL]\t!SA_SIGINFO handler was not called\n");
nerrs++;
}
}