// SPDX-License-Identifier: GPL-2.0 /* * Copyright 2017 John Sperbeck * * Test that an access to a mapped but inaccessible area causes a SEGV and * reports si_code == SEGV_ACCERR. */ #include <stdbool.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <signal.h> #include <sys/mman.h> #include <assert.h> #include <ucontext.h> #include "utils.h" static bool faulted; static int si_code; static void segv_handler(int n, siginfo_t *info, void *ctxt_v) { ucontext_t *ctxt = (ucontext_t *)ctxt_v; struct pt_regs *regs = ctxt->uc_mcontext.regs; faulted = true; si_code = info->si_code; regs->nip += 4; } int test_segv_errors(void) { struct sigaction act = { .sa_sigaction = segv_handler, .sa_flags = SA_SIGINFO, }; char c, *p = NULL; p = mmap(NULL, getpagesize(), 0, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); FAIL_IF(p == MAP_FAILED); FAIL_IF(sigaction(SIGSEGV, &act, NULL) != 0); faulted = false; si_code = 0; /* * We just need a compiler barrier, but mb() works and has the nice * property of being easy to spot in the disassembly. */ mb(); c = *p; mb(); FAIL_IF(!faulted); FAIL_IF(si_code != SEGV_ACCERR); faulted = false; si_code = 0; mb(); *p = c; mb(); FAIL_IF(!faulted); FAIL_IF(si_code != SEGV_ACCERR); return 0; } int main(void) { return test_harness(test_segv_errors, "segv_errors"); }