Re: [Qemu-devel] [PATCH v2 18/19] linux-user: Avoid possible misalignment in host_to_target_siginfo()

[Laurent Vivier]

Le 27/05/2016 à 16:52, Peter Maydell a écrit :
> host_to_target_siginfo() is implemented by a combination of
> host_to_target_siginfo_noswap() followed by tswap_siginfo().
> The first of these two functions assumes that the target_siginfo_t
> it is writing to is correctly aligned, but the pointer passed
> into host_to_target_siginfo() is directly from the guest and
> might be misaligned. Use a local variable to avoid this problem.
> (tswap_siginfo() does now correctly handle a misaligned destination.)

You mean the pointer from the guest can not be correctly aligned for the
guest?

Laurent
> 
> Signed-off-by: Peter Maydell <address@hidden>
> ---
>  linux-user/signal.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/linux-user/signal.c b/linux-user/signal.c
> index 8ea0cbf..7e2a80f 100644
> --- a/linux-user/signal.c
> +++ b/linux-user/signal.c
> @@ -400,8 +400,9 @@ static void tswap_siginfo(target_siginfo_t *tinfo,
>  
>  void host_to_target_siginfo(target_siginfo_t *tinfo, const siginfo_t *info)
>  {
> -    host_to_target_siginfo_noswap(tinfo, info);
> -    tswap_siginfo(tinfo, tinfo);
> +    target_siginfo_t tgt_tmp;
> +    host_to_target_siginfo_noswap(&tgt_tmp, info);
> +    tswap_siginfo(tinfo, &tgt_tmp);
>  }
>  
>  /* XXX: we support only POSIX RT signals are used. */
>