738b0cc5e9
Modify the overflow testing for sbrk. Bug: 15188366 Change-Id: Ia83f85f7c1789454d872279bd41f38f1ce6b8a34
74 lines
2.5 KiB
C++
74 lines
2.5 KiB
C++
/*
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* Copyright (C) 2008 The Android Open Source Project
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <errno.h>
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#include <unistd.h>
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#if __LP64__
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static void* __bionic_brk;
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#else
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void* __bionic_brk; // Accidentally exported by the NDK.
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#endif
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int brk(void* end_data) {
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__bionic_brk = __brk(end_data);
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if (__bionic_brk < end_data) {
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errno = ENOMEM;
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return -1;
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}
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return 0;
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}
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void* sbrk(ptrdiff_t increment) {
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// Initialize __bionic_brk if necessary.
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if (__bionic_brk == NULL) {
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__bionic_brk = __brk(NULL);
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}
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// Don't ask the kernel if we already know the answer.
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if (increment == 0) {
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return __bionic_brk;
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}
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// Avoid overflow.
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uintptr_t old_brk = reinterpret_cast<uintptr_t>(__bionic_brk);
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if ((increment > 0 && static_cast<uintptr_t>(increment) > (UINTPTR_MAX - old_brk)) ||
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(increment < 0 && static_cast<uintptr_t>(-increment) > old_brk)) {
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errno = ENOMEM;
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return reinterpret_cast<void*>(-1);
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}
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void* desired_brk = reinterpret_cast<void*>(old_brk + increment);
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__bionic_brk = __brk(desired_brk);
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if (__bionic_brk < desired_brk) {
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errno = ENOMEM;
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return reinterpret_cast<void*>(-1);
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}
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return reinterpret_cast<void*>(old_brk);
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}
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