Re: [PATCH 9/11] - UML - fix signal mask on delivery error

[Andrew Morton <akpm@osdl.org>]

(removed linux-kernel, added linux-arch)

Jeff Dike <jdike@addtoit.com> wrote:
>
> >From Bodo Stroesser - If the user stack limit is reached or the
> signal stack assigned with sigaltstack() is invalid when a user signal
> handler with SA_ONSTACK has to be started, the signal mask of the
> interrupted user program is modified. This happens because the mask,
> that should be used with the handler only, is written to
> "current->blocked" even if the handler could not be started. But
> without a handler, no rewrite of the original mask at sys_sigreturn
> will be done. A slightly different case is sys_sigsuspend(), where the
> mask is already modified when kern_do_signal() is started. "*oldset" and
> "current->blocked" are not equal here and thus current->blocked has to
> be set to *oldset, if an error occurs in handle_signal().
> For both cases I've written small tests, and with the patch the result
> is OK.
> This issue is relevant for other architectures too (e.g. i386, I've
> seen).

Could you send one of the test apps?  This is something which the arch
maintainers might want to look into fixing, thanks.


> Signed-off-by: Jeff Dike <jdike@addtoit.com>
> 
> Index: 2.6.9/arch/um/kernel/signal_kern.c
> ===================================================================
> --- 2.6.9.orig/arch/um/kernel/signal_kern.c	2004-11-12 16:24:18.000000000 -0500
> +++ 2.6.9/arch/um/kernel/signal_kern.c	2004-11-12 18:05:26.000000000 -0500
> @@ -79,7 +79,14 @@
>  	else
>  		err = setup_signal_stack_sc(sp, signr, ka, regs, oldset);
>  
> -	if (!err && !(ka->sa.sa_flags & SA_NODEFER)) {
> +	if(err){
> +		spin_lock_irq(&current->sighand->siglock);
> +		current->blocked = *oldset;
> +		recalc_sigpending();
> +		spin_unlock_irq(&current->sighand->siglock);
> +		force_sigsegv(signr, current);
> +	}
> +	else if(!(ka->sa.sa_flags & SA_NODEFER)){
>  		spin_lock_irq(&current->sighand->siglock);
>  		sigorsets(&current->blocked, &current->blocked, 
>  			  &ka->sa.sa_mask);
> @@ -87,9 +94,6 @@
>  		recalc_sigpending();
>  		spin_unlock_irq(&current->sighand->siglock);
>  	}
> -
> -	if(err)
> -		force_sigsegv(signr, current);
>  }
>  
>  static int kern_do_signal(struct pt_regs *regs, sigset_t *oldset)