/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* syscall_arg_fault.c - tests faults 32-bit fast syscall stack args
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* Copyright (c) 2018 Andrew Lutomirski
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*/
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#define _GNU_SOURCE
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#include <stdlib.h>
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#include <stdio.h>
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#include <stdbool.h>
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#include <errno.h>
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#include <unistd.h>
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#include <syscall.h>
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static int nerrs;
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#define X32_BIT 0x40000000UL
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static void check_enosys(unsigned long nr, bool *ok)
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{
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/* If this fails, a segfault is reasonably likely. */
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fflush(stdout);
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long ret = syscall(nr, 0, 0, 0, 0, 0, 0);
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if (ret == 0) {
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printf("[FAIL]\tsyscall %lu succeeded, but it should have failed\n", nr);
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*ok = false;
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} else if (errno != ENOSYS) {
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printf("[FAIL]\tsyscall %lu had error code %d, but it should have reported ENOSYS\n", nr, errno);
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*ok = false;
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}
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}
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static void test_x32_without_x32_bit(void)
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{
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bool ok = true;
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/*
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* Syscalls 512-547 are "x32" syscalls. They are intended to be
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* called with the x32 (0x40000000) bit set. Calling them without
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* the x32 bit set is nonsense and should not work.
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*/
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printf("[RUN]\tChecking syscalls 512-547\n");
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for (int i = 512; i <= 547; i++)
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check_enosys(i, &ok);
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/*
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* Check that a handful of 64-bit-only syscalls are rejected if the x32
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* bit is set.
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*/
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printf("[RUN]\tChecking some 64-bit syscalls in x32 range\n");
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check_enosys(16 | X32_BIT, &ok); /* ioctl */
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check_enosys(19 | X32_BIT, &ok); /* readv */
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check_enosys(20 | X32_BIT, &ok); /* writev */
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/*
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* Check some syscalls with high bits set.
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*/
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printf("[RUN]\tChecking numbers above 2^32-1\n");
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check_enosys((1UL << 32), &ok);
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check_enosys(X32_BIT | (1UL << 32), &ok);
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if (!ok)
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nerrs++;
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else
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printf("[OK]\tThey all returned -ENOSYS\n");
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}
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int main()
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{
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/*
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* Anyone diagnosing a failure will want to know whether the kernel
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* supports x32. Tell them.
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*/
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printf("\tChecking for x32...");
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fflush(stdout);
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if (syscall(39 | X32_BIT, 0, 0, 0, 0, 0, 0) >= 0) {
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printf(" supported\n");
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} else if (errno == ENOSYS) {
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printf(" not supported\n");
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} else {
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printf(" confused\n");
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}
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test_x32_without_x32_bit();
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return nerrs ? 1 : 0;
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}
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