Re: [PATCH 2/6] linux-user: Disable more prctl subcodes

[Laurent Vivier]

Le 20/12/2021 à 23:41, Philippe Mathieu-Daudé a écrit :
> On 12/20/21 22:41, Richard Henderson wrote:
> > Create a list of subcodes that we want to pass on, a list of
> > subcodes that should not be passed on because they would affect
> > the running qemu itself, and a list that probably could be
> > implemented but require extra work. Do not pass on unknown subcodes.
> >
> > Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> > ---
> >   linux-user/syscall.c | 56 ++++++++++++++++++++++++++++++++++++++++----
> >   1 file changed, 52 insertions(+), 4 deletions(-)
>
> > +    case PR_SET_SYSCALL_USER_DISPATCH:
> > +    case PR_GET_THP_DISABLE:
> > +    case PR_SET_THP_DISABLE:
> > +    case PR_GET_TSC:
> > +    case PR_SET_TSC:
> > +    case PR_GET_UNALIGN:
> > +    case PR_SET_UNALIGN:
> >       default:
>
> Unfortunately prctl values are not enumerated, so we can't remove
> the default case to catch new values at build time.
>
> Maybe a qemu_log_mask(LOG_UNIMP) call would help here? (only

Yes, I think a qemu_log_mask(LOG_UNIMP) for the default case would help.
> for default?)
>
> Regardless:
> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>

Reviewed-by: Laurent Vivier <laurent@vivier.eu>

> > -        /* Most prctl options have no pointer arguments */
> > -        return get_errno(prctl(option, arg2, arg3, arg4, arg5));
> > +        /* Disable to prevent the target disabling stuff we need. */
> > +        return -TARGET_EINVAL;
> >       }
> >   }
> >