93 lines
2.0 KiB
C
93 lines
2.0 KiB
C
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// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Copyright (c) 2021 Liam R. Howlett <liam.howlett@oracle.com>
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*/
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/*\
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* [Description]
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*
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* Expand brk() by at least 2 pages to ensure there is a newly created VMA
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* and not expanding the original due to multiple anon pages. mprotect() that
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* new VMA then brk() back to the original address therefore causing a munmap of
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* at least one full VMA.
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*/
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#include <unistd.h>
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#include <sys/mman.h>
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#include "tst_test.h"
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#include "lapi/syscalls.h"
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static void *brk_variants(void *addr)
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{
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void *brk_addr;
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if (tst_variant) {
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brk_addr = (void *)tst_syscall(__NR_brk, addr);
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} else {
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TST_EXP_PASS_SILENT(brk(addr), "brk()");
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brk_addr = (void *)sbrk(0);
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}
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return brk_addr;
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}
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static void brk_down_vmas(void)
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{
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void *brk_addr;
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if (tst_variant) {
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tst_res(TINFO, "Testing syscall variant");
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brk_addr = (void *)tst_syscall(__NR_brk, 0);
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} else {
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tst_res(TINFO, "Testing libc variant");
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brk_addr = (void *)sbrk(0);
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if (brk_addr == (void *)-1)
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tst_brk(TCONF, "sbrk() not implemented");
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/*
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* Check if brk itself is implemented: updating to the current break
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* should be a no-op.
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*/
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if (brk(brk_addr) != 0)
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tst_brk(TCONF, "brk() not implemented");
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}
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unsigned long page_size = getpagesize();
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void *addr = brk_addr + page_size;
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if (brk_variants(addr) < addr) {
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tst_res(TFAIL | TERRNO, "Cannot expand brk() by page size");
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return;
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}
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addr += page_size;
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if (brk_variants(addr) < addr) {
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tst_res(TFAIL | TERRNO, "Cannot expand brk() by 2x page size");
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return;
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}
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if (mprotect(addr - page_size, page_size, PROT_READ)) {
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tst_res(TFAIL | TERRNO, "Cannot mprotect new VMA");
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return;
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}
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addr += page_size;
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if (brk_variants(addr) < addr) {
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tst_res(TFAIL | TERRNO, "Cannot expand brk() after mprotect");
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return;
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}
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if (brk_variants(brk_addr) != brk_addr) {
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tst_res(TFAIL | TERRNO, "Cannot restore brk() to start address");
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return;
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}
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tst_res(TPASS, "munmap at least two VMAs of brk() passed");
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}
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static struct tst_test test = {
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.test_all = brk_down_vmas,
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.test_variants = 2,
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};
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