3093e71811
When a thread calls pthread_exit(3), ScopedSignalBlocker blocks all user-visible signals, but leaves internal-use signals 33/34/36/36/37. Signal 33 is used to unwind a thread for a backtrace, which can cause us to access the stack after it's been unmapped. (Avoiding this was the reason why we have the ScopedSignalBlocker in pthread_exit(3)!) Fix this (and other potential issues) by changing ScopedSignalBlocker to call __rt_sigprocmask(2) directly, so we don't mask out the internal-use signals. Bug: https://issuetracker.google.com/153624226 Test: not trivially reproducible Change-Id: I9b125ed41ddee4c5d33b45920f1d142e52db47cb
56 lines
1.7 KiB
C++
56 lines
1.7 KiB
C++
/*
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* Copyright (C) 2017 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#pragma once
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#include <signal.h>
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#include "platform/bionic/macros.h"
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// This code needs to really block all the signals, not just the user-visible
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// ones. We call __rt_sigprocmask(2) directly so we don't mask out our own
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// signals (https://issuetracker.google.com/153624226 was a pthread_exit(3)
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// crash because a request to dump the thread's stack came in as it was exiting).
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extern "C" int __rt_sigprocmask(int, const sigset64_t*, sigset64_t*, size_t);
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class ScopedSignalBlocker {
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public:
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// Block all signals.
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explicit ScopedSignalBlocker() {
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sigset64_t set;
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sigfillset64(&set);
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__rt_sigprocmask(SIG_BLOCK, &set, &old_set_, sizeof(sigset64_t));
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}
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// Block just the specified signal.
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explicit ScopedSignalBlocker(int signal) {
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sigset64_t set = {};
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sigaddset64(&set, signal);
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__rt_sigprocmask(SIG_BLOCK, &set, &old_set_, sizeof(sigset64_t));
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}
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~ScopedSignalBlocker() {
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reset();
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}
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void reset() {
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__rt_sigprocmask(SIG_SETMASK, &old_set_, nullptr, sizeof(sigset64_t));
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}
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sigset64_t old_set_;
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BIONIC_DISALLOW_COPY_AND_ASSIGN(ScopedSignalBlocker);
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};
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