Hi Andrej,
On Thu, Oct 17, 2024 at 9:47 AM Andrej Shadura
<andrew.shadura@xxxxxxxxxxxxxxx> wrote:
>
> On 09/10/2024 14:14, Andrej Shadura wrote:
> > Commit 9bf4e919ccad worked around an issue introduced after an
> > innocuous optimisation change in LLVM main:
> >
> >> len is defined as an 'int' because it is assigned from
> >> '__user int *optlen'. However, it is clamped against the result of
> >> sizeof(), which has a type of 'size_t' ('unsigned long' for 64-bit
> >> platforms). This is done with min_t() because min() requires
> >> compatible types, which results in both len and the result of
> >> sizeof() being casted to 'unsigned int', meaning len changes signs
> >> and the result of sizeof() is truncated. From there, len is passed
> >> to copy_to_user(), which has a third parameter type of 'unsigned
> >> long', so it is widened and changes signs again. This excessive
> >> casting in combination with the KCSAN instrumentation causes LLVM to
> >> fail to eliminate the __bad_copy_from() call, failing the build.
> >
> > The same issue occurs in rfcomm in functions rfcomm_sock_getsockopt
> > and rfcomm_sock_getsockopt_old.
> >
> > Change the type of len to size_t in both rfcomm_sock_getsockopt and
> > rfcomm_sock_getsockopt_old and replace min_t() with min().
>
> Any more reviews please? It would be great to have this fix merged :)
I was waiting to see if David had any more feedback, but if he doesn't
I'm happy to merge this later today.
> Thanks in advance.
>
> --
> Cheers,
> Andrej
>
--
Luiz Augusto von Dentz
