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https://github.com/jart/cosmopolitan.git
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379cd77078
On Windows, mmap() now chooses addresses transactionally. It reduces the risk of badness when interacting with the WIN32 memory manager. We don't throw darts anymore. There is also no more retry limit, since we recover from mystery maps more gracefully. The subroutine for combining adjacent maps has been rewritten for clarity. The print maps subroutine is better This change goes to great lengths to perfect the stack overflow code. On Windows you can now longjmp() out of a crash signal handler. Guard pages previously weren't being restored properly by the signal handler. That's fixed, so on Windows you can now handle a stack overflow multiple times. Great thought has been put into selecting the perfect SIGSTKSZ constants so you can save sigaltstack() memory. You can now use kprintf() with 512 bytes of stack available. The guard pages beneath the main stack are now recorded in the memory manager. This change fixes getcontext() so it works right with the %rax register.
292 lines
11 KiB
C
292 lines
11 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2021 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/assert.h"
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#include "libc/calls/calls.h"
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#include "libc/calls/struct/sigaction.h"
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#include "libc/calls/ucontext.h"
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#include "libc/dce.h"
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#include "libc/errno.h"
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#include "libc/intrin/describeflags.h"
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#include "libc/log/log.h"
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#include "libc/mem/gc.h"
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#include "libc/mem/mem.h"
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#include "libc/runtime/runtime.h"
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#include "libc/stdio/stdio.h"
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#include "libc/str/str.h"
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#include "libc/sysv/consts/auxv.h"
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#include "libc/sysv/consts/map.h"
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#include "libc/sysv/consts/o.h"
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#include "libc/sysv/consts/prot.h"
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#include "libc/sysv/consts/sa.h"
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#include "libc/sysv/consts/sig.h"
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#include "libc/testlib/testlib.h"
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#include "libc/x/x.h"
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#include "third_party/xed/x86.h"
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volatile bool gotsegv;
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volatile bool gotbusted;
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struct sigaction old[2];
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void SetUpOnce(void) {
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testlib_enable_tmp_setup_teardown();
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}
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#ifdef __x86_64__
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static const char kRet31337[] = {
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0xb8, 0x69, 0x7a, 0x00, 0x00, // mov $31337,%eax
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0xc3, // ret
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};
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#elif defined(__aarch64__)
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static const uint32_t kRet31337[] = {
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0x528f4d20, // mov w0,#31337
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0xd65f03c0, // ret
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};
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#else
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#error "unsupported architecture"
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#endif
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void SkipOverFaultingInstruction(struct ucontext *ctx) {
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#ifdef __x86_64__
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struct XedDecodedInst xedd;
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xed_decoded_inst_zero_set_mode(&xedd, XED_MACHINE_MODE_LONG_64);
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xed_instruction_length_decode(&xedd, (void *)ctx->uc_mcontext.rip, 15);
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ctx->uc_mcontext.rip += xedd.length;
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#elif defined(__aarch64__)
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ctx->uc_mcontext.pc += 4;
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#else
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#error "unsupported architecture"
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#endif
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}
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void OnSigSegv(int sig, siginfo_t *si, void *vctx) {
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struct ucontext *ctx = vctx;
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gotsegv = true;
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SkipOverFaultingInstruction(ctx);
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}
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void OnSigBus(int sig, siginfo_t *si, void *vctx) {
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struct ucontext *ctx = vctx;
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gotbusted = true;
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SkipOverFaultingInstruction(ctx);
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#if 0
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kprintf("SIGBUS%n");
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kprintf("si->si_signo = %G%n", si->si_signo);
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kprintf("si->si_errno = %s (%d)%n", _strerrno(si->si_errno),
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si->si_errno);
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kprintf("si->si_code = %s (%d)%n", DescribeSiCode(sig, si->si_code),
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si->si_code);
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kprintf("┌si->si_addr = %p%n", si->si_addr);
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kprintf("┼─────────────────%n");
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kprintf("│si->si_pid = %d (note: getpid() is %d)%n", si->si_pid, getpid());
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kprintf("│si->si_uid = %d%n", si->si_uid);
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kprintf("┼─────────────────%n");
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kprintf("│si->si_timerid = %d%n", si->si_timerid);
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kprintf("└si->si_overrun = %d%n", si->si_overrun);
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kprintf("si->si_value.sival_int = %d%n", si->si_value.sival_int);
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kprintf("si->si_value.sival_ptr = %p%n", si->si_value.sival_ptr);
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system(xasprintf("cat /proc/%d/map", getpid()));
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#endif
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}
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void SetUp(void) {
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struct sigaction sabus = {.sa_sigaction = OnSigBus,
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.sa_flags = SA_SIGINFO | SA_RESETHAND};
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struct sigaction sasegv = {.sa_sigaction = OnSigSegv,
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.sa_flags = SA_SIGINFO | SA_RESETHAND};
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unassert(!sigaction(SIGBUS, &sabus, old + 0));
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unassert(!sigaction(SIGSEGV, &sasegv, old + 1));
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gotbusted = false;
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gotsegv = false;
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}
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void TearDown(void) {
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unassert(!sigaction(SIGBUS, old + 0, 0));
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unassert(!sigaction(SIGSEGV, old + 1, 0));
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}
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TEST(mprotect, testOkMemory) {
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char *p = gc(memalign(getpagesize(), getpagesize()));
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p[0] = 0;
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ASSERT_NE(-1, mprotect(p, getpagesize(), PROT_READ | PROT_WRITE));
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p[0] = 1;
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EXPECT_EQ(1, p[0]);
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EXPECT_FALSE(gotsegv);
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EXPECT_FALSE(gotbusted);
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}
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TEST(mprotect, testSegfault_writeToReadOnlyAnonymous) {
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volatile char *p;
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p = gc(memalign(getpagesize(), getpagesize()));
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EXPECT_FALSE(gotsegv);
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p[0] = 1;
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EXPECT_FALSE(gotsegv);
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EXPECT_FALSE(gotbusted);
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EXPECT_NE(-1, mprotect((void *)p, getpagesize(), PROT_READ));
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__expropriate(p[0]);
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EXPECT_FALSE(gotsegv);
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EXPECT_FALSE(gotbusted);
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p[0] = 2;
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EXPECT_TRUE(gotsegv | gotbusted);
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EXPECT_EQ(1, p[0]);
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EXPECT_NE(-1, mprotect((void *)p, getpagesize(), PROT_READ | PROT_WRITE));
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}
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TEST(mprotect, testExecOnly_canExecute) {
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char *p = _mapanon(getpagesize());
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void (*f)(void) = (void *)p;
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memcpy(p, kRet31337, sizeof(kRet31337));
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ASSERT_SYS(0, 0, mprotect(p, getpagesize(), PROT_EXEC | PROT_READ));
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f();
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// On all supported platforms, PROT_EXEC implies PROT_READ. There is
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// one exception to this rule: Chromebook's fork of the Linux kernel
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// which has been reported, to have the ability to prevent a program
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// from reading its own code.
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ASSERT_SYS(0, 0, mprotect(p, getpagesize(), PROT_EXEC));
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f();
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munmap(p, getpagesize());
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}
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TEST(mprotect, testProtNone_cantEvenRead) {
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volatile char *p;
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p = gc(memalign(getpagesize(), getpagesize()));
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EXPECT_NE(-1, mprotect((void *)p, getpagesize(), PROT_NONE));
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__expropriate(p[0]);
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EXPECT_TRUE(gotsegv | gotbusted);
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EXPECT_NE(-1, mprotect((void *)p, getpagesize(), PROT_READ | PROT_WRITE));
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}
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TEST(mprotect, testExecJit_actuallyWorks) {
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int (*p)(void) = gc(memalign(getpagesize(), getpagesize()));
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memcpy(p, kRet31337, sizeof(kRet31337));
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EXPECT_NE(-1, mprotect(p, getpagesize(), PROT_EXEC));
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EXPECT_EQ(31337, p());
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EXPECT_FALSE(gotsegv);
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EXPECT_FALSE(gotbusted);
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EXPECT_NE(-1, mprotect(p, getpagesize(), PROT_READ | PROT_WRITE));
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}
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TEST(mprotect, testRwxMap_vonNeumannRules) {
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if (IsOpenbsd())
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return; // boo
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if (IsXnuSilicon())
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return; // boo
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int (*p)(void) = gc(memalign(getpagesize(), getpagesize()));
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memcpy(p, kRet31337, sizeof(kRet31337));
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EXPECT_NE(-1, mprotect(p, getpagesize(), PROT_READ | PROT_WRITE | PROT_EXEC));
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EXPECT_EQ(31337, p());
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EXPECT_FALSE(gotsegv);
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EXPECT_FALSE(gotbusted);
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EXPECT_NE(-1, mprotect(p, getpagesize(), PROT_READ | PROT_WRITE));
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}
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TEST(mprotect, testExecuteFlatFileMapOpenedAsReadonly) {
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if (IsXnuSilicon())
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return; // TODO(jart): Use APE Loader SIP workaround?
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int (*p)(void);
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size_t n = sizeof(kRet31337);
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ASSERT_SYS(0, 3, creat("return31337", 0755));
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ASSERT_SYS(0, n, write(3, kRet31337, n));
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ASSERT_SYS(0, 0, close(3));
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ASSERT_SYS(0, 3, open("return31337", O_RDONLY));
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EXPECT_NE(MAP_FAILED,
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(p = mmap(NULL, n, PROT_READ | PROT_EXEC, MAP_PRIVATE, 3, 0)));
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EXPECT_EQ(31337, p());
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EXPECT_FALSE(gotsegv);
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EXPECT_FALSE(gotbusted);
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ASSERT_SYS(0, 0, close(3));
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ASSERT_SYS(0, 0, munmap(p, n));
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}
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TEST(mprotect, testFileMap_canChangeToExecWhileOpenInRdwrMode) {
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int (*p)(void);
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size_t n = sizeof(kRet31337);
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ASSERT_SYS(0, 3, open("return31337", O_CREAT | O_TRUNC | O_RDWR, 0755));
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ASSERT_SYS(0, n, write(3, kRet31337, n));
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EXPECT_NE(MAP_FAILED,
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(p = mmap(NULL, n, PROT_READ | PROT_WRITE, MAP_PRIVATE, 3, 0)));
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EXPECT_NE(-1, mprotect(p, n, PROT_READ | PROT_EXEC));
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EXPECT_EQ(31337, p());
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EXPECT_FALSE(gotsegv);
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EXPECT_FALSE(gotbusted);
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ASSERT_SYS(0, 0, close(3));
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ASSERT_SYS(0, 0, munmap(p, n));
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}
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TEST(mprotect, testBadProt_failsEinval) {
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volatile char *p = gc(memalign(getpagesize(), getpagesize()));
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EXPECT_EQ(-1, mprotect((void *)p, 9999, -1));
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EXPECT_EQ(EINVAL, errno);
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}
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TEST(mprotect, testZeroSize_doesNothing) {
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volatile char *p = gc(memalign(getpagesize(), getpagesize()));
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EXPECT_NE(-1, mprotect((void *)p, 0, PROT_READ));
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p[0] = 1;
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EXPECT_FALSE(gotsegv);
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EXPECT_FALSE(gotbusted);
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}
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TEST(mprotect, image) {
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_Alignas(16384) static const char lol[16384] = {1, 2, 3};
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intptr_t i = (intptr_t)lol;
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asm("" : "+r"(i));
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char *p = (char *)i;
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EXPECT_SYS(0, 0, mprotect(p, 16384, PROT_READ | PROT_WRITE));
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EXPECT_EQ(2, ++p[0]);
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}
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TEST(mprotect, weirdSize) {
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char *p;
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EXPECT_NE(MAP_FAILED, (p = mmap(0, 1, PROT_READ | PROT_EXEC,
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MAP_PRIVATE | MAP_ANONYMOUS, -1, 0)));
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EXPECT_SYS(0, 0, mprotect(p, 2, PROT_NONE));
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EXPECT_SYS(0, 0, munmap(p, 1));
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}
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TEST(mprotect, outerOverlap) {
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if (IsWindows())
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return; // needs carving
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char *p;
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int gransz = getgransize();
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EXPECT_NE(MAP_FAILED, (p = mmap(0, gransz * 3, PROT_READ | PROT_EXEC,
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MAP_PRIVATE | MAP_ANONYMOUS, -1, 0)));
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EXPECT_TRUE(testlib_memoryexists(p + gransz * 0));
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EXPECT_TRUE(testlib_memoryexists(p + gransz * 1));
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EXPECT_TRUE(testlib_memoryexists(p + gransz * 2));
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EXPECT_SYS(0, 0, munmap(p, gransz));
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EXPECT_FALSE(testlib_memoryexists(p + gransz * 0));
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EXPECT_TRUE(testlib_memoryexists(p + gransz * 1));
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EXPECT_TRUE(testlib_memoryexists(p + gransz * 2));
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EXPECT_SYS(0, 0, munmap(p + gransz * 2, gransz));
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EXPECT_FALSE(testlib_memoryexists(p + gransz * 0));
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EXPECT_TRUE(testlib_memoryexists(p + gransz * 1));
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EXPECT_FALSE(testlib_memoryexists(p + gransz * 2));
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EXPECT_SYS(0, 0, mprotect(p, gransz * 3, PROT_NONE));
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EXPECT_FALSE(testlib_memoryexists(p + gransz * 0));
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EXPECT_FALSE(testlib_memoryexists(p + gransz * 1));
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EXPECT_FALSE(testlib_memoryexists(p + gransz * 2));
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EXPECT_SYS(0, 0, mprotect(p + gransz, gransz, PROT_READ));
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EXPECT_FALSE(testlib_memoryexists(p + gransz * 0));
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EXPECT_TRUE(testlib_memoryexists(p + gransz * 1));
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EXPECT_FALSE(testlib_memoryexists(p + gransz * 2));
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EXPECT_SYS(0, 0, munmap(p, gransz * 3));
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EXPECT_FALSE(testlib_memoryexists(p + gransz * 0));
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EXPECT_FALSE(testlib_memoryexists(p + gransz * 1));
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EXPECT_FALSE(testlib_memoryexists(p + gransz * 2));
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}
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