[llvm-dev] Sanitizers and static linking

[David Greene via llvm-dev]

Ok, that makes sense.  Should there be code to test the result of dlsym
and report an error to the user?  Faulting simply because one uses
--static during the link stage isn't very friendly.  It would be nice to
get an error with a helpful message about linking libc dynamically.

Would there be interest in a patch to implement this?

                          -David

Reid Kleckner via llvm-dev <llvm-dev at lists.llvm.org> writes:

> Saying that sanitizers "do not support static linking" seems strange
> because we strongly advise users to link the sanitizer libraries
> themselves statically. This gives the best user experience, because it
> puts the interceptors into the executable, so they always come first
> in dynamic symbol search order.
>
> What I think you are saying is that the sanitizers do not support
> linking statically with libc. This is probably true. It would be
> difficult to modify the interceptors to work when libc is linked
> statically, so it's probably not supported.
>
> Hopefully that explains why the sanitizer libraries are static, but
> they don't exactly support linking with -static.
>
> On Thu, Aug 23, 2018 at 10:04 AM David Greene via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
>
>     I am guessing that sanitizers are not supported with static
>     linking.
>     The AddressSanitizer document says so explicitly but the others do
>     not.
>     Yet the interceptors use dlsym to set up certain system calls, so
>     by
>     definition they can't support static linking.
>     
>     Given that sanitizers won't work with static linking, why are
>     static
>     libraries created for them?
>     
>     Should there be an error check in the interceptor code for dlsym
>     returning nullptr? I just spent a bunch of time tracking down a
>     problem
>     that turned out to be dlsym returning nullptr due to static
>     linking.
>     
>     It seems like either users should not be able to link sanitizer
>     runtime
>     when linking statically or there should be a runtime check that
>     dlsym
>     doesn't return nullptr. Ideally both.
>     
>     -David
>     _______________________________________________
>     LLVM Developers mailing list
>     llvm-dev at lists.llvm.org
>     http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev