crashpad/util/win/safe_terminate_process.h
Mark Mentovai e04194afd9 win: Wrap TerminateProcess() to accept cdecl patches on x86
TerminateProcess(), like most of the Windows API, is declared WINAPI,
which is __stdcall on 32-bit x86. That means that the callee,
TerminateProcess() itself, is responsible for cleaning up parameters on
the stack on return. In https://crashpad.chromium.org/bug/179, crashes
in ExceptionHandlerServer::OnNonCrashDumpEvent() were observed in ways
that make it evident that TerminateProcess() has been patched with a
__cdecl routine. The crucial difference between __stdcall and __cdecl is
that the caller is responsible for stack parameter cleanup in __cdecl.
The mismatch means that nobody cleans parameters from the stack, and the
stack pointer has an unexpected value, which in the case of the Crashpad
handler crash, results in TerminateProcess()’s second argument
erroneously being used as the lock address in the call to
ReleaseSRWLockExclusive() or LeaveCriticalSection().

As a workaround, on 32-bit x86, call through SafeTerminateProcess(), a
custom assembly routine that’s compatible with either __stdcall or
__cdecl implementations of TerminateProcess() by not trusting the value
of the stack pointer on return from that function. Instead, the stack
pointer is restored directly from the frame pointer.

Bug: crashpad:179
Test: crashpad_util_test SafeTerminateProcess.*, others
Change-Id: If9508f4eb7631020ea69ddbbe4a22eb335cdb325
Reviewed-on: https://chromium-review.googlesource.com/481180
Reviewed-by: Scott Graham <scottmg@chromium.org>
2017-04-19 17:45:32 +00:00

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// Copyright 2017 The Crashpad Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef CRASHPAD_UTIL_WIN_SAFE_TERMINATE_PROCESS_H_
#define CRASHPAD_UTIL_WIN_SAFE_TERMINATE_PROCESS_H_
#include <windows.h>
#include "build/build_config.h"
namespace crashpad {
//! \brief Calls `TerminateProcess()`.
//!
//! `TerminateProcess()` has been observed in the wild as being patched badly on
//! 32-bit x86: its patched with code adhering to the `cdecl` (caller clean-up)
//! convention, although its supposed to be `stdcall` (callee clean-up). The
//! mix-up means that neither caller nor callee perform parameter clean-up from
//! the stack, causing the stack pointer to have an unexpected value on return
//! from the patched function. This typically results in a crash shortly
//! thereafter. See <a href="https://crashpad.chromium.org/bug/179">Crashpad bug
//! 179</a>.
//!
//! On 32-bit x86, this replacement function calls `TerminateProcess()` without
//! making any assumptions about the stack pointer on its return. As such, its
//! compatible with the badly patched `cdecl` version as well as the native
//! `stdcall` version (and other less badly patched versions).
//!
//! Elsewhere, this function calls `TerminateProcess()` directly without any
//! additional fanfare.
//!
//! Call this function instead of `TerminateProcess()` anywhere that
//! `TerminateProcess()` would normally be called.
bool SafeTerminateProcess(HANDLE process, UINT exit_code);
#if !defined(ARCH_CPU_X86)
inline bool SafeTerminateProcess(HANDLE process, UINT exit_code) {
return TerminateProcess(process, exit_code) != FALSE;
}
#endif // !ARCH_CPU_X86
} // namespace crashpad
#endif // CRASHPAD_UTIL_WIN_SAFE_TERMINATE_PROCESS_H_