[llvm] r271053 - [libFuzzer] use __sanitizer_set_report_fd with -close_fd_mask. This allows us to keep asan reports when closing target's stderr

[Kostya Serebryany via llvm-commits]

Author: kcc
Date: Fri May 27 16:46:22 2016
New Revision: 271053

URL: http://llvm.org/viewvc/llvm-project?rev=271053&view=rev
Log:
[libFuzzer] use __sanitizer_set_report_fd with -close_fd_mask. This allows us to keep asan reports when closing target's stderr

Modified:
    llvm/trunk/docs/LibFuzzer.rst
    llvm/trunk/lib/Fuzzer/FuzzerIO.cpp
    llvm/trunk/lib/Fuzzer/test/fuzzer.test

Modified: llvm/trunk/docs/LibFuzzer.rst
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/docs/LibFuzzer.rst?rev=271053&r1=271052&r2=271053&view=diff
==============================================================================
--- llvm/trunk/docs/LibFuzzer.rst (original)
+++ llvm/trunk/docs/LibFuzzer.rst Fri May 27 16:46:22 2016
@@ -273,9 +273,8 @@ The most important command line options
   If 1 (default) and if LeakSanitizer is enabled
   try to detect memory leaks during fuzzing (i.e. not only at shut down).
 ``-close_fd_mask``
-  Indicate output streams to close at startup. Be careful, this will also
-  remove diagnostic output from the tools in use; for example the messages
-  AddressSanitizer_ sends to ``stderr``/``stdout`` will also be lost.
+  Indicate output streams to close at startup. Be careful, this will
+  remove diagnostic output from target code (e.g. messages on assert failure).
 
    - 0 (default): close neither ``stdout`` nor ``stderr``
    - 1 : close ``stdout``

Modified: llvm/trunk/lib/Fuzzer/FuzzerIO.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Fuzzer/FuzzerIO.cpp?rev=271053&r1=271052&r2=271053&view=diff
==============================================================================
--- llvm/trunk/lib/Fuzzer/FuzzerIO.cpp (original)
+++ llvm/trunk/lib/Fuzzer/FuzzerIO.cpp Fri May 27 16:46:22 2016
@@ -18,6 +18,10 @@
 #include <cstdarg>
 #include <cstdio>
 
+extern "C" {
+__attribute__((weak)) void __sanitizer_set_report_fd(void *);
+}
+
 namespace fuzzer {
 
 static FILE *OutputFile = stderr;
@@ -122,6 +126,8 @@ void DupAndCloseStderr() {
     FILE *NewOutputFile = fdopen(OutputFd, "w");
     if (NewOutputFile) {
       OutputFile = NewOutputFile;
+      if (__sanitizer_set_report_fd)
+        __sanitizer_set_report_fd(reinterpret_cast<void*>(OutputFd));
       close(2);
     }
   }

Modified: llvm/trunk/lib/Fuzzer/test/fuzzer.test
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Fuzzer/test/fuzzer.test?rev=271053&r1=271052&r2=271053&view=diff
==============================================================================
--- llvm/trunk/lib/Fuzzer/test/fuzzer.test (original)
+++ llvm/trunk/lib/Fuzzer/test/fuzzer.test Fri May 27 16:46:22 2016
@@ -11,7 +11,9 @@ RUN: LLVMFuzzer-SimpleTest -only_ascii=1
 RUN: LLVMFuzzer-SimpleCmpTest -max_total_time=1 2>&1 | FileCheck %s --check-prefix=MaxTotalTime
 MaxTotalTime: Done {{.*}} runs in {{.}} second(s)
 
-RUN: not LLVMFuzzer-NullDerefTest 2>&1 | FileCheck %s --check-prefix=NullDerefTest
+RUN: not LLVMFuzzer-NullDerefTest                  2>&1 | FileCheck %s --check-prefix=NullDerefTest
+RUN: not LLVMFuzzer-NullDerefTest -close_fd_mask=3 2>&1 | FileCheck %s --check-prefix=NullDerefTest
+NullDerefTest: ERROR: AddressSanitizer: SEGV on unknown address
 NullDerefTest: Test unit written to ./crash-
 RUN: not LLVMFuzzer-NullDerefTest  -artifact_prefix=ZZZ 2>&1 | FileCheck %s --check-prefix=NullDerefTestPrefix
 NullDerefTestPrefix: Test unit written to ZZZcrash-