From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from mail.virtlab.unibo.it (mail.virtlab.unibo.it [130.136.161.50])
	by smtp.subspace.kernel.org (Postfix) with ESMTP id 57F65256C8B
	for <linux-kernel@vger.kernel.org>; Sat,  4 Jul 2026 14:25:23 +0000 (UTC)
Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=130.136.161.50
ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116;
	t=1783175126; cv=none; b=dymP4R3YuDGqtiBdpWO/8S3nj0JVV81xBRPgqhSX/7KTnzwcYsd/J6+mu/mzJyeEH30cXngJmGmUysHbMQ63qk7mCaKZfcZNtPsovNwoORfxTy9I1KiiAwB6rcLHWsdRAp6N69arxSdBNkPLVRU5Qyso1ivuHQEM7Mq7YVxMZlU=
ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org;
	s=arc-20240116; t=1783175126; c=relaxed/simple;
	bh=vkY5Id5sgYfddu2dMfb1hrpho8ScVH/tZfuSA7+R93g=;
	h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version:
	 Content-Type:Content-Disposition:In-Reply-To; b=Hc3jmOJCv/+9hZWO+I35G7Tdg3KVBYnJEeZmZZJZUhMp3hPk0kkRPRHztbS7s1BYVfQoLFD1wz1BVFJtv31iYEiflUE7c6lTXOqqq6q1+jwn29cdbjO9S4pFixG5oDsfYHo50RLCgNsBaSk2xp0yO4oueVBqrfDt2JsxTRs8Snw=
ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=cs.unibo.it; spf=pass smtp.mailfrom=cs.unibo.it; dkim=pass (1024-bit key) header.d=cs.unibo.it header.i=@cs.unibo.it header.b=Jg1Tfs35; arc=none smtp.client-ip=130.136.161.50
Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=cs.unibo.it
Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=cs.unibo.it
Authentication-Results: smtp.subspace.kernel.org;
	dkim=pass (1024-bit key) header.d=cs.unibo.it header.i=@cs.unibo.it header.b="Jg1Tfs35"
Received: from cs.unibo.it (unknown [94.32.99.206])
	by mail.virtlab.unibo.it (Postfix) with ESMTPSA id B30CF1C0095;
	Sat,  4 Jul 2026 16:25:21 +0200 (CEST)
DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=cs.unibo.it;
	s=virtlab; t=1783175122;
	bh=vkY5Id5sgYfddu2dMfb1hrpho8ScVH/tZfuSA7+R93g=;
	h=Date:From:To:Cc:Subject:References:In-Reply-To:From;
	b=Jg1Tfs35SijAABenMpZ2f3RNSABsMMxP65mTkjNn3G4xpjCuJxYiJta8O67CRHXHM
	 zyWrq8WkcCDvZiLEBlbJpK60sTCXEFEbCpRnnSjI+XRdNb84zczcHw/H6fh+ybrz25
	 QLV48Uqs74j326l/nN+oNQokbRwoKPRLP1MQ5fWo=
Date: Sat, 4 Jul 2026 16:25:20 +0200
From: Renzo Davoli <renzo@cs.unibo.it>
To: Oleg Nesterov <oleg@redhat.com>
Cc: linux-kernel@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>,
	Shuah Khan <shuah@kernel.org>, Alexey Gladkov <legion@kernel.org>,
	Eugene Syromyatnikov <evgsyr@gmail.com>,
	Davide Berardi <berardi.dav@gmail.com>,
	strace-devel@lists.strace.io, "Dmitry V . Levin" <ldv@strace.io>
Subject: Re: [PATCH 1/2] ptrace: PTRACE_SET_SYSCALL_INFO syscall skipping
 support
Message-ID: <akkX0AmPacHkY9S4@cs.unibo.it>
References: <20260704083359.632410-1-renzo@cs.unibo.it>
 <20260704083359.632410-2-renzo@cs.unibo.it>
 <akjr3HZoLOdBOj1a@redhat.com>
Precedence: bulk
X-Mailing-List: linux-kernel@vger.kernel.org
List-Id: <linux-kernel.vger.kernel.org>
List-Subscribe: <mailto:linux-kernel+subscribe@vger.kernel.org>
List-Unsubscribe: <mailto:linux-kernel+unsubscribe@vger.kernel.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <akjr3HZoLOdBOj1a@redhat.com>

You are right, fixing in v2.
renzo

On Sat, Jul 04, 2026 at 01:17:48PM +0200, Oleg Nesterov wrote:
> On 07/04, Renzo Davoli wrote:
> >
> > -	/* Changing the type of the system call stop is not supported yet. */
> > -	if (ptrace_get_syscall_info_op(child) != info.op)
> > -		return -EINVAL;
> > +	/*
> > +	 * Changing the type of the system call stop is not allowed, with the
> > +	 * following exception:
> > +	 * PTRACE_SYSCALL_INFO_SECCOMP or PTRACE_SYSCALL_INFO_ENTRY can be changed
> > +	 * to PTRACE_SYSCALL_INFO_EXIT to skip the system call
> > +	 */
> > +
> > +	if (ptrace_get_syscall_info_op(child) != info.op) {
> > +		if (info.op != PTRACE_SYSCALL_INFO_EXIT)
> > +			return -EINVAL;
> > +		skip_syscall = true;
> > +	}
> 
> Ah... I forgot that ptrace_get_syscall_info_op() can return _NONE.
> 
> We should not allow _NONE -> _EXIT transition.
> 
> Oleg.