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// Copyright 2018 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// PLEASE READ BEFORE CHANGING THIS FILE!
//
// This file implements the out of bounds trap handler for
// WebAssembly. Exception handlers are notoriously difficult to get
// right, and getting it wrong can lead to security
// vulnerabilities. In order to minimize this risk, here are some
// rules to follow.
//
// 1. Do not introduce any new external dependencies. This file needs
// to be self contained so it is easy to audit everything that a
// trap handler might do.
//
// 2. Any changes must be reviewed by someone from the crash reporting
// or security team. See OWNERS for suggested reviewers.
//
// For more information, see https://goo.gl/yMeyUY.
//
// This file contains most of the code that actually runs in an exception
// handler context. Some additional code is used both inside and outside the
// trap handler. This code can be found in handler-shared.cc.
#include "src/trap-handler/handler-inside-win.h"
#include <windows.h>
#include "src/trap-handler/trap-handler-internal.h"
#include "src/trap-handler/trap-handler.h"
namespace v8 {
namespace internal {
namespace trap_handler {
bool TryHandleWasmTrap(EXCEPTION_POINTERS* exception) {
// Ensure the faulting thread was actually running Wasm code.
if (!IsThreadInWasm()) {
return false;
}
// Clear g_thread_in_wasm_code, primarily to protect against nested faults.
g_thread_in_wasm_code = false;
const EXCEPTION_RECORD* record = exception->ExceptionRecord;
if (record->ExceptionCode != EXCEPTION_ACCESS_VIOLATION) {
return false;
}
uintptr_t fault_addr = reinterpret_cast<uintptr_t>(record->ExceptionAddress);
uintptr_t landing_pad = 0;
if (TryFindLandingPad(fault_addr, &landing_pad)) {
exception->ContextRecord->Rip = landing_pad;
// We will return to wasm code, so restore the g_thread_in_wasm_code flag.
g_thread_in_wasm_code = true;
return true;
}
// If we get here, it's not a recoverable wasm fault, so we go to the next
// handler. Leave the g_thread_in_wasm_code flag unset since we do not return
// to wasm code.
return false;
}
LONG HandleWasmTrap(EXCEPTION_POINTERS* exception) {
if (TryHandleWasmTrap(exception)) {
return EXCEPTION_CONTINUE_EXECUTION;
}
return EXCEPTION_CONTINUE_SEARCH;
}
} // namespace trap_handler
} // namespace internal
} // namespace v8
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