Re: [PATCH] kcov: don't instrument with UBSAN

[Stephen Rothwell]

Hi all,

On Wed, 9 Dec 2020 10:54:39 -0800 Kees Cook <keescook@xxxxxxxxxxxx> wrote:
>
> On Wed, Dec 09, 2020 at 11:01:52AM +0100, Dmitry Vyukov wrote:
> > Both KCOV and UBSAN use compiler instrumentation. If UBSAN detects a bug
> > in KCOV, it may cause infinite recursion via printk and other common
> > functions. We already don't instrument KCOV with KASAN/KCSAN for this
> > reason, don't instrument it with UBSAN as well.
> > 
> > As a side effect this also resolves the following gcc warning:
> > 
> > conflicting types for built-in function '__sanitizer_cov_trace_switch';
> > expected 'void(long unsigned int,  void *)' [-Wbuiltin-declaration-mismatch]
> > 
> > It's only reported when kcov.c is compiled with any of the sanitizers
> > enabled. Size of the arguments is correct, it's just that gcc uses 'long'
> > on 64-bit arches and 'long long' on 32-bit arches, while kernel type is
> > always 'long long'.
> > 
> > Reported-by: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
> > Suggested-by: Marco Elver <elver@xxxxxxxxxx>
> > Signed-off-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>  
> 
> Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
> 
> Thanks for chasing this down!
> 
> Andrew, can you add this to the stack of ubsan patches you're carrying,
> please?

Added to linux-next today.

-- 
Cheers,
Stephen Rothwell

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