hwasan_checks.h
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//===-- hwasan_checks.h -----------------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file is a part of HWAddressSanitizer.
//
//===----------------------------------------------------------------------===//
#ifndef HWASAN_CHECKS_H
#define HWASAN_CHECKS_H
#include "hwasan_mapping.h"
#include "sanitizer_common/sanitizer_common.h"
namespace __hwasan {
template <unsigned X>
__attribute__((always_inline)) static void SigTrap(uptr p) {
#if defined(__aarch64__)
(void)p;
// 0x900 is added to do not interfere with the kernel use of lower values of
// brk immediate.
register uptr x0 asm("x0") = p;
asm("brk %1\n\t" ::"r"(x0), "n"(0x900 + X));
#elif defined(__x86_64__)
// INT3 + NOP DWORD ptr [EAX + X] to pass X to our signal handler, 5 bytes
// total. The pointer is passed via rdi.
// 0x40 is added as a safeguard, to help distinguish our trap from others and
// to avoid 0 offsets in the command (otherwise it'll be reduced to a
// different nop command, the three bytes one).
asm volatile(
"int3\n"
"nopl %c0(%%rax)\n" ::"n"(0x40 + X),
"D"(p));
#else
// FIXME: not always sigill.
__builtin_trap();
#endif
// __builtin_unreachable();
}
// Version with access size which is not power of 2
template <unsigned X>
__attribute__((always_inline)) static void SigTrap(uptr p, uptr size) {
#if defined(__aarch64__)
register uptr x0 asm("x0") = p;
register uptr x1 asm("x1") = size;
asm("brk %2\n\t" ::"r"(x0), "r"(x1), "n"(0x900 + X));
#elif defined(__x86_64__)
// Size is stored in rsi.
asm volatile(
"int3\n"
"nopl %c0(%%rax)\n" ::"n"(0x40 + X),
"D"(p), "S"(size));
#else
__builtin_trap();
#endif
// __builtin_unreachable();
}
__attribute__((always_inline, nodebug)) static bool PossiblyShortTagMatches(
tag_t mem_tag, uptr ptr, uptr sz) {
tag_t ptr_tag = GetTagFromPointer(ptr);
if (ptr_tag == mem_tag)
return true;
if (mem_tag >= kShadowAlignment)
return false;
if ((ptr & (kShadowAlignment - 1)) + sz > mem_tag)
return false;
#ifndef __aarch64__
ptr = UntagAddr(ptr);
#endif
return *(u8 *)(ptr | (kShadowAlignment - 1)) == ptr_tag;
}
enum class ErrorAction { Abort, Recover };
enum class AccessType { Load, Store };
template <ErrorAction EA, AccessType AT, unsigned LogSize>
__attribute__((always_inline, nodebug)) static void CheckAddress(uptr p) {
uptr ptr_raw = p & ~kAddressTagMask;
tag_t mem_tag = *(tag_t *)MemToShadow(ptr_raw);
if (UNLIKELY(!PossiblyShortTagMatches(mem_tag, p, 1 << LogSize))) {
SigTrap<0x20 * (EA == ErrorAction::Recover) +
0x10 * (AT == AccessType::Store) + LogSize>(p);
if (EA == ErrorAction::Abort)
__builtin_unreachable();
}
}
template <ErrorAction EA, AccessType AT>
__attribute__((always_inline, nodebug)) static void CheckAddressSized(uptr p,
uptr sz) {
if (sz == 0)
return;
tag_t ptr_tag = GetTagFromPointer(p);
uptr ptr_raw = p & ~kAddressTagMask;
tag_t *shadow_first = (tag_t *)MemToShadow(ptr_raw);
tag_t *shadow_last = (tag_t *)MemToShadow(ptr_raw + sz);
for (tag_t *t = shadow_first; t < shadow_last; ++t)
if (UNLIKELY(ptr_tag != *t)) {
SigTrap<0x20 * (EA == ErrorAction::Recover) +
0x10 * (AT == AccessType::Store) + 0xf>(p, sz);
if (EA == ErrorAction::Abort)
__builtin_unreachable();
}
uptr end = p + sz;
uptr tail_sz = end & 0xf;
if (UNLIKELY(tail_sz != 0 &&
!PossiblyShortTagMatches(
*shadow_last, end & ~(kShadowAlignment - 1), tail_sz))) {
SigTrap<0x20 * (EA == ErrorAction::Recover) +
0x10 * (AT == AccessType::Store) + 0xf>(p, sz);
if (EA == ErrorAction::Abort)
__builtin_unreachable();
}
}
} // end namespace __hwasan
#endif // HWASAN_CHECKS_H