25de3f98b8
Summary: GWP-ASan's PRNG didn't use Initial-Exec TLS. Fix that to ensure that we don't have infinite recursion, and also that we don't allocate a DTV on Android when GWP-ASan is touched. Test coverage ensuring that the sample counter is UINT32_MAX for an uninitialised GWP-ASan is provided by gwp_asan/tests/late_init.cpp. Reviewers: pcc, cferris Reviewed By: pcc Subscribers: #sanitizers, llvm-commits, rprichard, eugenis Tags: #sanitizers, #llvm Differential Revision: https://reviews.llvm.org/D74135
32 lines
1022 B
C++
32 lines
1022 B
C++
//===-- random.cpp ----------------------------------------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "gwp_asan/random.h"
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#include "gwp_asan/common.h"
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#include <time.h>
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// Initialised to a magic constant so that an uninitialised GWP-ASan won't
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// regenerate its sample counter for as long as possible. The xorshift32()
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// algorithm used below results in getRandomUnsigned32(0xff82eb50) ==
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// 0xfffffea4.
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GWP_ASAN_TLS_INITIAL_EXEC uint32_t RandomState = 0xff82eb50;
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namespace gwp_asan {
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void initPRNG() {
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RandomState = time(nullptr) + getThreadID();
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}
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uint32_t getRandomUnsigned32() {
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RandomState ^= RandomState << 13;
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RandomState ^= RandomState >> 17;
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RandomState ^= RandomState << 5;
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return RandomState;
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}
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} // namespace gwp_asan
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