Re: [PATCH for-4.19?] libelf: avoid UB in elf_xen_feature_{get,set}()

["Oleksii K." <oleksii.kurochko@xxxxxxxxx>]

On Thu, 2024-06-20 at 17:07 +0100, Andrew Cooper wrote:
> On 20/06/2024 4:34 pm, Jan Beulich wrote:
> > When the left shift amount is up to 31, the shifted quantity wants
> > to be
> > of unsigned int (or wider) type.
> > 
> > While there also adjust types: get doesn't alter the array and
> > returns a
> > boolean, while both don't really accept negative "nr". Drop a stray
> > blank each as well.
> > 
> > Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> 
> Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> 
> +1 for 4.19.
Release-Acked-By: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>

~ Oleksii

> 
> > ---
> > Really I wonder why these exist at all; they're effectively
> > test_bit()
> > and __set_bit() in hypervisor terms, and iirc something like that
> > exists
> > in the tool stack as well.
> 
> The toolstack has tools/libs/ctrl/xc_bitops.h but they're not API
> compatible with Xen.
> 
> They're long-granular rather than int-granular, have swapped
> arguments,
> and are non-LOCKed.
> 
> ~Andrew