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62 lines
1.7 KiB
C
62 lines
1.7 KiB
C
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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/*
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* A poison value that can be used to fill a memory space with
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* an address that leads to a safe crash when dereferenced.
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*/
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#ifndef mozilla_Poison_h_
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#define mozilla_Poison_h_
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#include "mozilla/Assertions.h"
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#include "mozilla/StandardInteger.h"
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#include "mozilla/Types.h"
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MOZ_BEGIN_EXTERN_C
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extern MFBT_DATA uintptr_t gMozillaPoisonValue;
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/**
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* @return the poison value.
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*/
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inline uintptr_t mozPoisonValue()
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{
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return gMozillaPoisonValue;
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}
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/**
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* Overwrite the memory block of aSize bytes at aPtr with the poison value.
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* aPtr MUST be aligned at a sizeof(uintptr_t) boundary.
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* Only an even number of sizeof(uintptr_t) bytes are overwritten, the last
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* few bytes (if any) is not overwritten.
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*/
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inline void mozWritePoison(void* aPtr, size_t aSize)
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{
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const uintptr_t POISON = mozPoisonValue();
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char* p = (char*)aPtr;
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char* limit = p + aSize;
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MOZ_ASSERT((uintptr_t)aPtr % sizeof(uintptr_t) == 0, "bad alignment");
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MOZ_ASSERT(aSize >= sizeof(uintptr_t), "poisoning this object has no effect");
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for (; p < limit; p += sizeof(uintptr_t)) {
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*((uintptr_t*)p) = POISON;
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}
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}
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/**
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* Initialize the poison value.
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* This should only be called once.
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*/
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extern MFBT_API void mozPoisonValueInit();
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/* Values annotated by CrashReporter */
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extern MFBT_DATA uintptr_t gMozillaPoisonBase;
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extern MFBT_DATA uintptr_t gMozillaPoisonSize;
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MOZ_END_EXTERN_C
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#endif /* mozilla_Poison_h_ */
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