Re: [PATCH] signal: Make the si_code check in rt_[tg]sigqueueinfo stricter

[Amanieu d'Antras]

On Mon, Oct 12, 2015 at 4:54 PM, Oleg Nesterov <oleg@xxxxxxxxxx> wrote:
> Yes, copy_siginfo_to_user() does __put_user((short)from->si_code).
> But SI_FROMUSER/SI_FROMKERNEL are internal kernel checks, we mostly
> use them in copy_siginfo_to_user().
>
> And note that if ->si_code < 0 we simply do __copy_to_user(), so
> userspace can't see something which looks like "from kernel", in
> this case we do not truncate ->si_code.

Ah my bad, I seem to have missed that case. So copy_siginfo_to_user
seems to be safe, but it is still an issue for copy_siginfo_to_user32
which doesn't have this check.

Maybe this should be fixed in the compat code instead?
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