88 lines
3.5 KiB
C++
88 lines
3.5 KiB
C++
/*
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* Copyright (C) 2020 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 "platform/bionic/android_unsafe_frame_pointer_chase.h"
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#include "platform/bionic/mte.h"
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#include "platform/bionic/pac.h"
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#include "private/bionic_defs.h"
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#include "pthread_internal.h"
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__BIONIC_WEAK_FOR_NATIVE_BRIDGE
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extern "C" __LIBC_HIDDEN__ uintptr_t __get_thread_stack_top() {
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return __get_thread()->stack_top;
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}
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/*
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* Implement fast stack unwinding for stack frames with frame pointers. Stores at most num_entries
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* return addresses to buffer buf. Returns the number of available return addresses, which may be
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* greater than num_entries.
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*
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* This function makes no guarantees about its behavior on encountering a frame built without frame
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* pointers, except that it should not crash or enter an infinite loop, and that any frames prior to
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* the frame built without frame pointers should be correct.
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*
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* This function is only meant to be used with memory safety tools such as sanitizers which need to
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* take stack traces efficiently. Normal applications should use APIs such as libunwindstack or
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* _Unwind_Backtrace.
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*/
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__attribute__((no_sanitize("address", "hwaddress"))) size_t android_unsafe_frame_pointer_chase(
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uintptr_t* buf, size_t num_entries) {
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// Disable MTE checks for the duration of this function, since we can't be sure that following
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// next_frame pointers won't cause us to read from tagged memory. ASAN/HWASAN are disabled here
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// for the same reason.
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ScopedDisableMTE x;
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struct frame_record {
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uintptr_t next_frame, return_addr;
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};
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auto begin = reinterpret_cast<uintptr_t>(__builtin_frame_address(0));
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auto end = __get_thread_stack_top();
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stack_t ss;
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if (sigaltstack(nullptr, &ss) == 0 && (ss.ss_flags & SS_ONSTACK)) {
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end = reinterpret_cast<uintptr_t>(ss.ss_sp) + ss.ss_size;
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}
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size_t num_frames = 0;
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while (1) {
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auto* frame = reinterpret_cast<frame_record*>(begin);
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if (num_frames < num_entries) {
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buf[num_frames] = __bionic_clear_pac_bits(frame->return_addr);
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}
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++num_frames;
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if (frame->next_frame < begin + sizeof(frame_record) || frame->next_frame >= end ||
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frame->next_frame % sizeof(void*) != 0) {
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break;
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}
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begin = frame->next_frame;
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}
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return num_frames;
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}
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