On 07.09.2019 01:07, Kamil Rytarowski wrote:
> On 07.09.2019 00:41, Thomas Klausner wrote:
>> On Sat, Sep 07, 2019 at 12:36:49AM +0200, Kamil Rytarowski wrote:
>>> Sanitizing compiler is available without MKSANITIZER.
>>
>> I tried (on 9.99.10 from Aug 26):
>>
>> wiz@yt:~> clang -fsanitize=address -g memory-leak.c
>> wiz@yt:~> ASAN_OPTIONS=detect_leaks=1 ./a.out
>> ==16509==AddressSanitizer: detect_leaks is not supported on this platform.
>>
> 
> The version of Clang/LLVM in base as of today (clang 7.x, compiler-rt
> 8.x) does not support LSan/NetBSD.
> 
> LSan/NetBSD is supported in Clang/LLVM 9.0.0.
> 
> Michal Gorny works on porting LLVM 9.0.0 to the base in this moment.
> 
> As an intermediate step we have updated to LLVM 8.x and NetBSD-current
> from HEAD.
> 
> https://github.com/mgorny/netbsd-src/tree/llvm8
> 
> Next step is to update to Clang/LLVM 9.0.0 prerelease snapshot, the
> final release of 9.0.0 is still not formally out.
> 
> NB. LSan in LLVM 9.0.0 will have one flaw on NetBSD. It will report
> false positives in strict detection of leaks on process termination.
> This functionality is called from an atexit(3) callback, and the
> callback is fired from libc and before freeing memory of it.
> 
> There is need to invent a solution to this false-positive.
> 
>>> libutil is built with a sanitizer.
>>>
>>> This means that the code in libutil is instrumented and contains calls
>>> to sanitizer runtime.
>>>
>>> The runtime is linked into programs, not libraries.
>>>
>>> This means that there is need to build each program in this setup with a
>>> sanitizer.
>>
>> Ok, thanks for the explanation.
>>
> 
> There are some alternative approaches, but I don't want to make

things more complex here.

> 
>>> Every application that dynamically links with an instrumented library
>>> has to be prebuilt with a sanitizer.
>>>
>>>> Do I have to recompile all of pkgsrc, and if yes, why?
>>>
>>> Basically yes, there is need to recompile all of pkgsrc.
>>
>> Do I need to use any particular settings or will this automatically
>> work in such a userland?
>>
> 
> If we want to combine pkgsrc with a MKSANITIZER host, we want to reuse
> the same CPPFLAGS, CFLAGS, CXXFLAGS and LDFLAGS as in basesystem.
> 
> This is by default:
> 
> CPPFLAGS=-D_REENTRANT
> CFLAGS=-fsanitize=address
> CXXFLAGS=-fsanitize=address
> LDFLAGS=-fsanitize=address
> 
>>> However ASan and UBSan can be often used on the top of non-sanitized
>>> libraries and this will work decently finding problems in an
>>> application, but skipping issues called in libraries.
>>>
>>> MSan and TSan are more sensitive here and need full sanitization.
>>
>> I'm currently mostly interested in the leak sanitizer.
>> But perhaps that's not available yet, or at least not in 9.99.10?
>>  Thomas
>>
> 
> I could backport LSan/LLVM for NetBSD-9 if there would be a request.
> However before that I would prefer to address the mentioned
> false-positive from the atexit(3) callback. I have originally
> rescheduled it for NetBSD-10.
> 
> For LSan there is no need for MKSANITIZER as all free/malloc/similar
> calls are intercepted always regardless of instrumenting the code.
> 
> It's also possible to use -fsanitize=leak, without -fsanitize=address.
> It's actually a better idea here if we want to catch only leaks as
> ASan/NetBSD is still not perfect.
> 


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