[sanitizer] New attempt at using runtime checks for Android logging
Summary: This is a second attempt after D40100 induced racey crashes with ASan (due to `__android_log_write` and the `strncpy` interceptor on API >= 21). This new version checks the runtime API level to be <= `ANDROID_KITKAT` for the use of `__android_log_write`, otherwise we use `syslog`, which should conform with the previous behavior. Unfortunately despite numerous efforts I couldn't reproduce the original crashes in my environments so I couldn't test that the fix was actually preventing crashes. Reviewers: eugenis Reviewed By: eugenis Subscribers: llvm-commits, srhines, kubamracek Differential Revision: https://reviews.llvm.org/D40149 llvm-svn: 318659
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@ -48,10 +48,6 @@
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#include <android/api-level.h>
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#endif
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#if SANITIZER_ANDROID && __ANDROID_API__ < 21
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#include <android/log.h>
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#endif
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#if !SANITIZER_ANDROID
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#include <elf.h>
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#include <unistd.h>
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@ -536,12 +532,9 @@ uptr GetRSS() {
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return rss * GetPageSizeCached();
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}
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// 64-bit Android targets don't provide the deprecated __android_log_write.
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// Starting with the L release, syslog() works and is preferable to
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// __android_log_write.
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#if SANITIZER_LINUX
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#if SANITIZER_ANDROID
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# if SANITIZER_ANDROID
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static atomic_uint8_t android_log_initialized;
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void AndroidLogInit() {
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@ -552,35 +545,55 @@ void AndroidLogInit() {
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static bool ShouldLogAfterPrintf() {
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return atomic_load(&android_log_initialized, memory_order_acquire);
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}
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#else
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extern "C" SANITIZER_WEAK_ATTRIBUTE
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int async_safe_write_log(int pri, const char* tag, const char* msg);
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extern "C" SANITIZER_WEAK_ATTRIBUTE
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int __android_log_write(int prio, const char* tag, const char* msg);
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// ANDROID_LOG_INFO is 4, but can't be resolved at runtime.
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#define SANITIZER_ANDROID_LOG_INFO 4
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// async_safe_write_log is a new public version of __libc_write_log that is
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// used behind syslog. It is preferable to syslog as it will not do any dynamic
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// memory allocation or formatting.
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// If the function is not available, syslog is preferred for L+ (it was broken
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// pre-L) as __android_log_write triggers a racey behavior with the strncpy
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// interceptor. Fallback to __android_log_write pre-L.
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void WriteOneLineToSyslog(const char *s) {
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if (&async_safe_write_log) {
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async_safe_write_log(SANITIZER_ANDROID_LOG_INFO, GetProcessName(), s);
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} else if (AndroidGetApiLevel() > ANDROID_KITKAT) {
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syslog(LOG_INFO, "%s", s);
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} else {
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CHECK(&__android_log_write);
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__android_log_write(SANITIZER_ANDROID_LOG_INFO, nullptr, s);
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}
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}
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extern "C" SANITIZER_WEAK_ATTRIBUTE
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void android_set_abort_message(const char *);
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void SetAbortMessage(const char *str) {
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if (&android_set_abort_message)
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android_set_abort_message(str);
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}
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# else
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void AndroidLogInit() {}
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static bool ShouldLogAfterPrintf() { return true; }
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#endif // SANITIZER_ANDROID
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void WriteOneLineToSyslog(const char *s) {
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#if SANITIZER_ANDROID &&__ANDROID_API__ < 21
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__android_log_write(ANDROID_LOG_INFO, NULL, s);
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#else
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syslog(LOG_INFO, "%s", s);
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#endif
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}
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void WriteOneLineToSyslog(const char *s) { syslog(LOG_INFO, "%s", s); }
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void SetAbortMessage(const char *str) {}
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# endif // SANITIZER_ANDROID
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void LogMessageOnPrintf(const char *str) {
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if (common_flags()->log_to_syslog && ShouldLogAfterPrintf())
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WriteToSyslog(str);
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}
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#if SANITIZER_ANDROID
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extern "C" __attribute__((weak)) void android_set_abort_message(const char *);
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void SetAbortMessage(const char *str) {
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if (&android_set_abort_message) android_set_abort_message(str);
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}
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#else
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void SetAbortMessage(const char *str) {}
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#endif
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#endif // SANITIZER_LINUX
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#endif // SANITIZER_LINUX
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} // namespace __sanitizer
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