[cfe-dev] [UBSan] Is static linking supported?

[Vedant Kumar via cfe-dev]

> On Aug 23, 2018, at 11:27 AM, Richard Smith <richard at metafoo.co.uk> wrote:
> 
> On Thu, 23 Aug 2018, 11:13 Vedant Kumar via cfe-dev, <cfe-dev at lists.llvm.org <mailto:cfe-dev at lists.llvm.org>> wrote:
> > On Aug 23, 2018, at 10:59 AM, David Greene <dag at cray.com <mailto:dag at cray.com>> wrote:
> > 
> > According to Reid Kleckner over on llvm-dev sanitizers will not work at
> > all with a statically-linked libc, as the interceptors use dlsym to set
> > up calls to sigaction and the like.  That matched my findings while
> > debugging the problem we're seeing.
> 
> Good point, that might be the issue here.
> 
> UBSan, unlike the other sanitizers, was explicitly designed to not perform any interception. It's possible that has changed in the interim, of course ...

Ah, you're right, I don't think that's changed.

The standalone version of the UBSan runtime used on Windows does install its own signal handlers. Maybe that causes a bad interaction with Troy's program?

vedant

> 
> > If sanitizers are supposed to work
> > with static linking, then it seems like the dependence on dlsym needs to
> > be broken.
> > 
> > Otherwise, the sanitizers should catch a nullptr return value from dlsym
> > and report a friendly user error message.  I can write a patch to do
> > that if it seems like a good idea.  Even when linking dynamically, it
> > would be good to check the return value of dlsym and report the error to
> > the user.
> 
> + 1.
> 
> vedant
> 
> 
> > 
> >                           -David
> > 
> > Vedant Kumar via cfe-dev <cfe-dev at lists.llvm.org <mailto:cfe-dev at lists.llvm.org>> writes:
> > 
> >> On some platforms it's possible to statically link against the
> >> ASan/UBSan runtimes using the undocumented -static-libsan option. The
> >> default behavior on Darwin, Android, and Fuchsia is to link against a
> >> DSO.
> >> 
> >>    On Aug 23, 2018, at 8:57 AM, Troy Johnson via cfe-dev
> >>    <cfe-dev at lists.llvm.org <mailto:cfe-dev at lists.llvm.org>> wrote:
> >> 
> >> 
> >> 
> >> 
> >>    The address sanitizer is documented as not supported with static
> >>    linking, but UBSan does not include the same disclaimer. UBSan
> >>    does not work for me with statically-linked executables. Instead,
> >>    the executables segfault immediately when attempting to install
> >>    signal handlers. Is this expected?
> >> 
> >> No, that's not expected :). Could you share the options you used to
> >> compile and link it, and the backtrace you get?
> >> 
> >> vedant
> >> 
> >> 
> >> 
> >>    -Troy
> >> 
> >> 
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