Re: [boost] Test failures on sanitize memory - are they caused by lightweight_test?

On Wednesday, March 11, 2015 05:43 PM, Andrey Semashev wrote:

On Wed, Mar 11, 2015 at 12:32 PM, Fletcher, John P wrote:

...

There is a test set on develop called BenPope x86_64 Ubuntu - phoenix - adapt_function / clang-linux-3.6~msan~c14_libc++

This runs this command line for example on the Phoenix test "adapt_function":

"clang++-3.6" -c -x c++ -std=c++1y -stdlib=libc++ -fsanitize=memory -O0 -fno-inline -Wall -fPIC -m64 -DBOOST_ALL_NO_LIB=1 -I".." -o "/home/ben/development/boost/test/build/develop/results/boost/bin.v2/libs/phoenix/test/adapt_function.test/clang-linux-3.6~msan~c14_libc++/debug/address-model-64/architecture-x86/debug-symbols-off/function/adapt_function.o" "../libs/phoenix/test/function/adapt_function.cpp"

There are numerous failures with this test set on Phoenix and I set out to find out why.

Most of the failures are like this:

SUMMARY: MemorySanitizer: use-of-uninitialized-value ??:0 std::__1::basic_ostream& std::__1::__put_character_sequence(std::__1::basic_ostream&, char const*, unsigned long) Exiting

I think this is coming from the boost::report_errors function defined in boost/core/lightweight_test.hpp

I have put some temporary tests on to develop for Phoenix which contain only various calls to test the lightweight test. These are called aa_test0 to 3 so they will come at the top of the table. Unfortunately tests are not reporting at the moment so I don't have any results.

There are also failures on the testing of Boost Core with the same test set.

I thought I would report this without waiting for the results in the hope that it can be sorted out for the 1.58.0 release.

This looks like a string insertion operator implementation. I don't see how the string memory could be uninitialized since there are only literals used in report_errors(), as well as other functions, unless you use BOOST_ERROR with uninitialized buffer as the message string. I suspect a false positive. Does MSan report an error for this code sample:

#include <iostream>

int main() { std::cerr << "Hello, world!" << std::endl; return 0; }

Yes. ben@yyls03:~/development/test$ ./a.out ==4752== WARNING: MemorySanitizer: use-of-uninitialized-value #0 0x7f0103b09f3f in std::__1::basic_ostream& std::__1::__put_character_sequence(std::__1::basic_ostream&, char const*, unsigned long) (/home/ben/development/test/a.out+0x8bf3f) #1 0x7f0103b09602 in std::__1::basic_ostream& std::__1::operator<< (std::__1::basic_ostream&, char const*) (/home/ben/development/test/a.out+0x8b602) #2 0x7f0103b094d6 in main (/home/ben/development/test/a.out+0x8b4d6) #3 0x7f0102462ec4 in __libc_start_main /build/buildd/eglibc-2.19/csu/libc-start.c:287 #4 0x7f0103ab4f7e in _start (/home/ben/development/test/a.out+0x36f7e) SUMMARY: MemorySanitizer: use-of-uninitialized-value ??:0 std::__1::basic_ostream& std::__1::__put_character_sequence

(std::__1::basic_ostream&, char const*, unsigned long) Exiting

I've added it to the blacklist now, hopefully I have the correct incantation and significantly reduce the false positives. Ben