Re: lib/51363: ubsan (undef behaviour sanitizer) faults

[Joerg Sonnenberger <joerg%bec.de@localhost>]

On Mon, Aug 01, 2016 at 06:25:01PM +0000, David Holland wrote:
> The following reply was made to PR lib/51363; it has been noted by GNATS.
> 
> From: David Holland <dholland-bugs%netbsd.org@localhost>
> To: gnats-bugs%NetBSD.org@localhost
> Cc: 
> Subject: Re: lib/51363: ubsan (undef behaviour sanitizer) faults
> Date: Mon, 1 Aug 2016 18:22:39 +0000
> 
>  On Sun, Jul 31, 2016 at 11:10:01PM +0000, bch wrote:
>   >  This is something I don't understand --
>   >  
>   >  I'm using clang from pkgsrc, and there are *no* ubsan components
>   >  installed that I can see. The clang documentation says that issuing
>   >  -fsanitize=* might only instrument the code, or require a lib for
>   >  runtime support. W/ the -fsanitize=undefined clang reports that it
>   >  wants to be linked to ubsan, and linking (w/ clang, which is supposed
>   >  to be used to pick the correct ubsan), still links as you see.
>  
>  Me either; unfortunately, I don't know much about it. I asked Joerg
>  and the only helpful information I was able to acquire is that it
>  shouldn't be using the gcc library.
>  
>  My guess would be that (maybe at config time when you built it) clang
>  detected the gcc libubsan and decided it should use that; or
>  alternatively it's just generating -lubsan and assuming the library
>  that finds is going to be the right one.
>  
>  I have no idea how it's supposed to work. Probably the best bet is to
>  find a clang list to ask on :-/

It wasn't even clear from the start that this is about the pkgsrc clang.
That one doesn't include any of the runtime libraries, so no ubsan
either. It is expected to be available, the compiler driver itself
doesn't check. There is currently no upstream support for any of the
sanitizers for NetBSD. I've refrained so far from committing any time to
it as the architecture is questionable (IMO) and the implementation of
the system call stubs via syscall(2) is horrible too.

Joerg