From 38b21e5ba3f2ee5c8a6473ed20e6fa1946bdd2e3 Mon Sep 17 00:00:00 2001 From: Ethan Chen Date: Tue, 25 Sep 2018 00:11:05 -0700 Subject: [PATCH 2/6] Actually restore pre-P mutex behavior Apps built against versions < P may not actually expect the EBUSY return code, and may crash or otherwise misbehave. Check for target SDK versions earlier than P when performing the IsMutexDestroyed check so any invocation of HandleUsingDestroyedMutex is bypassed and pre-P mutex behavior is restored. See 9e989f12d1186231d97dac6d038db7955acebdf3 for the change that introduced this new behavior. Change-Id: I45f8882c9527c63eed1ef5820a5004b8958d58ea --- libc/bionic/pthread_mutex.cpp | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) diff --git a/libc/bionic/pthread_mutex.cpp b/libc/bionic/pthread_mutex.cpp index f92184e50..f006bb92d 100644 --- a/libc/bionic/pthread_mutex.cpp +++ b/libc/bionic/pthread_mutex.cpp @@ -783,16 +783,23 @@ static int MutexLockWithTimeout(pthread_mutex_internal_t* mutex, bool use_realti } // namespace NonPI static inline __always_inline bool IsMutexDestroyed(uint16_t mutex_state) { - return mutex_state == 0xffff; + if (android_get_application_target_sdk_version() >= __ANDROID_API_P__) { + return mutex_state == 0xffff; + } + return false; } // Inlining this function in pthread_mutex_lock() adds the cost of stack frame instructions on // ARM64. So make it noinline. static int __attribute__((noinline)) HandleUsingDestroyedMutex(pthread_mutex_t* mutex, const char* function_name) { - if (android_get_application_target_sdk_version() >= __ANDROID_API_P__) { - __fortify_fatal("%s called on a destroyed mutex (%p)", function_name, mutex); - } + __fortify_fatal("%s called on a destroyed mutex (%p)", function_name, mutex); + return EBUSY; +} + +static int __always_inline HandleUsingDestroyedMutex(pthread_mutex_t* mutex, + const char* function_name) { + __fortify_fatal("%s called on a destroyed mutex (%p)", function_name, mutex); return EBUSY; } -- 2.17.1