Re: [PATCH v2 3/4] linux-user: fix TARGET_NSIG and _NSIG uses

[Peter Maydell]

On Tue, 4 Feb 2020 at 17:11, Laurent Vivier <address@hidden> wrote:
>
> Valid signal numbers are between 1 (SIGHUP) and SIGRTMAX.
>
> System includes define _NSIG to SIGRTMAX + 1, but
> QEMU (like kernel) defines TARGET_NSIG to TARGET_SIGRTMAX.
>
> Fix all the checks involving the signal range.
>
> Signed-off-by: Laurent Vivier <address@hidden>
> ---
>
> Notes:
>     v2: replace i, j by target_sig, host_sig
>
>  linux-user/signal.c | 52 ++++++++++++++++++++++++++++++++-------------
>  1 file changed, 37 insertions(+), 15 deletions(-)
>
> diff --git a/linux-user/signal.c b/linux-user/signal.c
> index 246315571c09..c1e664f97a7c 100644
> --- a/linux-user/signal.c
> +++ b/linux-user/signal.c
> @@ -30,6 +30,15 @@ static struct target_sigaction sigact_table[TARGET_NSIG];

Optional follow-on patch: make sigact_table[] also size
TARGET_NSIG + 1, for consistency with target_to_host_signal_table[],
and remove all the "- 1"s when we index into it.


> @@ -492,10 +514,10 @@ static void signal_table_init(void)
>          if (host_to_target_signal_table[host_sig] == 0) {
>              host_to_target_signal_table[host_sig] = host_sig;
>          }
> -    }
> -    for (host_sig = 1; host_sig < _NSIG; host_sig++) {
>          target_sig = host_to_target_signal_table[host_sig];
> -        target_to_host_signal_table[target_sig] = host_sig;
> +        if (target_sig <= TARGET_NSIG) {
> +            target_to_host_signal_table[target_sig] = host_sig;
> +        }

Why does this hunk apparently delete the for() line ?

Why do we need the if() -- surely there should never be any
entries in host_to_target_signal_table[] that aren't
valid target signal numbers ?

>      }
>  }
>
> @@ -518,7 +540,7 @@ void signal_init(void)
>      act.sa_sigaction = host_signal_handler;
>      for(i = 1; i <= TARGET_NSIG; i++) {
>  #ifdef TARGET_GPROF
> -        if (i == SIGPROF) {
> +        if (i == TARGET_SIGPROF) {
>              continue;
>          }
>  #endif
> --

thanks
-- PMM