crashpad/util/linux/initial_signal_dispositions.h
Joshua Peraza c4cc4e6ac9 android: initialize signal dispositions
Bionic installs signal handlers which request crash
dumps from Android's debuggerd, but there are errors
in how signals which aren't automatically re-raised
are handled on Marshmallow (API 23).

Before requesting a dump, Bionic acquires a lock to
communicate with debuggerd and expecting imminent
death, never releases it.

While handling the dump request, debuggerd allows
the dying process to continue before
ptrace-detaching it. So, when Bionic manually
re-raises a signal, it is intercepted by debuggerd
and the dying process is allowed to live.

Bionic restores SIG_DFL for the signal it's just
handled, but if a different crash signal is later
recieved, Bionic attempts to reacquire the lock to
communicate with debuggerd and blocks forever.

Disable Bionic's signal handlers for these signals
on Marshmallow.

Bug: chromium:1050178
Change-Id: Ia1fc5a24161a95931684d092ba8fee2f0dfbbdbb
Reviewed-on: https://chromium-review.googlesource.com/c/crashpad/crashpad/+/2134513
Reviewed-by: Mark Mentovai <mark@chromium.org>
2020-04-08 17:21:05 +00:00

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// Copyright 2020 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_LINUX_INITIAL_SIGNAL_DISPOSITIONS_H
#define CRASHPAD_UTIL_LINUX_INITIAL_SIGNAL_DISPOSITIONS_H
namespace crashpad {
//! \brief Establishes signal dispositions for a process based on the platform.
//!
//! Default signal dispositions are normally configured by the kernel, but
//! additional signal handlers might be installed by dependent or preloaded
//! libraries, e.g. Bionic normally installs signal handlers which log stack
//! traces to Android's logcat.
//!
//! This function initializes signal dispositions when the default dispositions
//! provided by the platform are broken. This function must be called before any
//! application level signal handlers have been installed and should be called
//! early in the process lifetime to reduce the chance of any broken signal
//! handlers being triggered.
//!
//! When running on Android M (API 23), this function installs `SIG_DFL` for
//! signals: `SIGABRT`, `SIGFPE`, `SIGPIPE`, `SIGSTKFLT`, and `SIGTRAP`.
//!
//! \return `true` on success. Otherwise `false` with a message logged.
bool InitializeSignalDispositions();
} // namespace crashpad
#endif // CRASHPAD_UTIL_LINUX_INITIAL_SIGNAL_DISPOSITIONS_H