Re: [Qemu-devel] [PATCH 1/1] tci: eliminate UB due to unaligned reads

[Anatoly Trosinenko]

Can rewriting TCI in such a way that every operation is aligned at 4- or
even 8-byte boundary fix the situation or are there some more serious
problems?

2018-03-03 16:57 GMT+03:00 Richard Henderson <address@hidden>:

> On 03/03/2018 12:54 AM, Anatoly Trosinenko wrote:
> > Ping.
> > Patchwork link: http://patchwork.ozlabs.org/patch/866732/
> > <http://patchwork.ozlabs.org/patch/866732/>
> > Patchew link:
> > http://patchew.org/QEMU/20180127134908.24095-1-
> address@hidden/
> > <http://patchew.org/QEMU/20180127134908.24095-1-
> address@hidden/>
> >
> > The code in tcg/tci.c reads some data from TCI bytecode through
> > pointer dereferencing. As far as I know unaligned reads in such a way are
> > undefined behavior and compiling with -fsanitize=undefined enumerated
> > them as such at run-time.
>
> This is exactly one of the reasons why I have urged for TCI to be
> abandoned.
>
> While your patch works, it is *enormously* inefficient for hosts that
> require it.
>
>
> r~
>



-- 
С уважением,
Анатолий Тросиненко
e-mail: address@hidden