[compiler-rt] r310089 - [compiler-rt] Check for empty buffer in Addr2LineProcess::ReadFromSymbolizer

[Alex Shlyapnikov via llvm-commits]

Author: alekseyshl
Date: Fri Aug  4 11:39:36 2017
New Revision: 310089

URL: http://llvm.org/viewvc/llvm-project?rev=310089&view=rev
Log:
[compiler-rt] Check for empty buffer in Addr2LineProcess::ReadFromSymbolizer

This fixes a bug in the ReadFromSymbolizer method of the
Addr2LineProcess class; if the input is too large, the returned buffer
will be null and will consequently fail the CHECK. The proposed fix is
to simply check if the buffer consists of only a null-terminator and
return if so (in effect skipping that frame). I tested by running one of
the unit tests both before and after my change.

Submitted on behalf of david-y-lam.

Reviewers: eugenis, alekseyshl, kcc

Reviewed By: alekseyshl

Differential Revision: https://reviews.llvm.org/D36207

Modified:
    compiler-rt/trunk/lib/sanitizer_common/sanitizer_symbolizer_libcdep.cc
    compiler-rt/trunk/lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cc

Modified: compiler-rt/trunk/lib/sanitizer_common/sanitizer_symbolizer_libcdep.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_symbolizer_libcdep.cc?rev=310089&r1=310088&r2=310089&view=diff
==============================================================================
--- compiler-rt/trunk/lib/sanitizer_common/sanitizer_symbolizer_libcdep.cc (original)
+++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_symbolizer_libcdep.cc Fri Aug  4 11:39:36 2017
@@ -454,7 +454,7 @@ bool SymbolizerProcess::ReadFromSymboliz
     if (ReachedEndOfOutput(buffer, read_len))
       break;
     if (read_len + 1 == max_length) {
-      Report("WARNING: Symbolizer buffer too small");
+      Report("WARNING: Symbolizer buffer too small\n");
       read_len = 0;
       break;
     }

Modified: compiler-rt/trunk/lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cc?rev=310089&r1=310088&r2=310089&view=diff
==============================================================================
--- compiler-rt/trunk/lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cc (original)
+++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cc Fri Aug  4 11:39:36 2017
@@ -272,6 +272,10 @@ class Addr2LineProcess : public Symboliz
   bool ReadFromSymbolizer(char *buffer, uptr max_length) override {
     if (!SymbolizerProcess::ReadFromSymbolizer(buffer, max_length))
       return false;
+    // The returned buffer is empty when output is valid, but exceeds
+    // max_length.
+    if (*buffer == '\0')
+      return true;
     // We should cut out output_terminator_ at the end of given buffer,
     // appended by addr2line to mark the end of its meaningful output.
     // We cannot scan buffer from it's beginning, because it is legal for it