From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201])
	(using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
	(No client certificate requested)
	by smtp.subspace.kernel.org (Postfix) with ESMTPS id E387037FF52
	for <linux-kernel@vger.kernel.org>; Tue, 17 Mar 2026 18:34:53 +0000 (UTC)
Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201
ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116;
	t=1773772494; cv=none; b=gb23zjAJ+ybVaFXvxyKAq0uF5f6PvoKhGm0TGYMiZ54snK7yaaJW4YJIqJ8JZxHLV8mo3mO4OY0l5yB1o6obQRPdeXlqM/eMQdClfECdnx0yawnqEEkr+jl6L/3igwv/L27hSP21tWGITdYnCq5zIKeZ1u0rtvmJYpzk4dSe3Sk=
ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org;
	s=arc-20240116; t=1773772494; c=relaxed/simple;
	bh=RVsjb7gSf8Tl+ZYDVu7R87RYo7eeBrQ5V3crBd21s4Q=;
	h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References:
	 Mime-Version:Content-Type; b=BxdDZ878R6Ck9qrs/9QP9/KWWXCJ+iEyw/72/51+dII+WiTtdD8Li/LwrXgV58PaAL+5IQyG7btdiZs7hyyy52yh95g4vy2ZLEWNHmSFAibbWdi6su+KzYRknsFiYUMH7LePC9soFxP0bO92+7wKIMNRm4I5HUjmG/+gNkke9mM=
ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=VJmIiWTA; arc=none smtp.client-ip=10.30.226.201
Authentication-Results: smtp.subspace.kernel.org;
	dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="VJmIiWTA"
Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5FEFDC4CEF7;
	Tue, 17 Mar 2026 18:34:53 +0000 (UTC)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org;
	s=korg; t=1773772493;
	bh=RVsjb7gSf8Tl+ZYDVu7R87RYo7eeBrQ5V3crBd21s4Q=;
	h=Date:From:To:Cc:Subject:In-Reply-To:References:From;
	b=VJmIiWTA0SPyUd6NSFdCQFTKb6GeSYwPjILc5D1E8i7ClalIhZ9mdBAqtzS0SHYYU
	 At3POUaIk2b3XJJmmlb19kMgI80FrM9kOY8UrTQuTHQe0p2cmad7gzZMCXbMDHBqqo
	 Cq4rvbeMeBVC4cE8g4+V9vm0ZsVBfhPy9BnerRmI=
Date: Tue, 17 Mar 2026 11:34:52 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Deepanshu Kartikey <kartikey406@gmail.com>,
 linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH -mm v2] do_notify_parent: sanitize the valid_signal()
 checks
Message-Id: <20260317113452.cede9a514dfed36a1cb0e5a9@linux-foundation.org>
In-Reply-To: <abld-ilvMEZ7VgMw@redhat.com>
References: <20260316151956.563558-1-kartikey406@gmail.com>
	<abld-ilvMEZ7VgMw@redhat.com>
X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu)
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-Transfer-Encoding: 7bit

On Tue, 17 Mar 2026 14:58:18 +0100 Oleg Nesterov <oleg@redhat.com> wrote:

> Now that kernel_clone() checks valid_signal(args->exit_signal), the "sig"
> argument of do_notify_parent() must always be valid or we have a bug.
> 
> However, do_notify_parent() only checks that sig != -1 at the start, then
> it does another valid_signal() check before __send_signal_locked().
> 
> This is confusing. Change do_notify_parent() to WARN and return early if
> valid_signal(sig) is false.

Sashiko has a question:
	https://sashiko.dev/#/patchset/abld-ilvMEZ7VgMw%40redhat.com