From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.netfilter.org (mail.netfilter.org [217.70.190.124]) (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 6EE815695; Wed, 9 Sep 2026 00:52:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.70.190.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788915148; cv=none; b=VZcqHDxa/hQ4LWSIPL/6NQXWEBGHekgCCanq2W+sFqLjChwyCErnt3GVigEYwbwpGFhCh5dQxL7Gog4hg6jS/dwLVx9eDp8Gcf6qGSCn410+qH2n2OmuPl6egGuMRxHV+4b8R/JmrigLWeF8v+E3ZSx/1+5CQHLvsSuC2LmwKbY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788915148; c=relaxed/simple; bh=Drg/l6eNiJdS6WrlfQrpnPJ76x1G5CGd7qHtm5jtorQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=bCSYCD3yqXXzbUuBdoemde6r9ps8JB7Uihb1Ecq+O/bWwbtW09f4dn/oAJrAkxNpLAKaD5o1Fvo92HxTv1LzefXoxxk4vdDDhegUGVd2UaDqC5RcIXd2emXxVEoQmxRoVOP7UwGQOguao2upxhuxTzK7TCQkafph86VeQ4v+FIg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=netfilter.org; spf=pass smtp.mailfrom=netfilter.org; dkim=pass (2048-bit key) header.d=netfilter.org header.i=@netfilter.org header.b=JyPVbB8s; arc=none smtp.client-ip=217.70.190.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=netfilter.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=netfilter.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=netfilter.org header.i=@netfilter.org header.b="JyPVbB8s" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=netfilter.org; s=2025; t=1788915144; bh=PdGrfA7zAJp8SMGp43M+kuZoPzHGQOyKC+mFwVh5MdE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=JyPVbB8sokRxp9wH5rtHPwiP5BmZGjxP4vvpGtrxjWYPSXDJMdBGwcvgvtua7g3w1 fpHSFbq4X473mFXMC8BRQugNouEwQ0pTo+BlwdQsaJCBph5qKMk8awXinvVgoZAzRm MQnIJ96RUHRjz+XLfW+MtDt1Saf2g0A8wJgG7I9pO7mUBaRt1JXLip1T0SNHMYv9GE 3H6f+gV7MPAheRxGENC+/u9NEBM3GWRTZDLhuU2M8OrXUiTPnhoj7mDr8J32LM+tUY UJkVOo8L0ayfZQsBzckOUMkC3o/sNrR7XOnmHIZcG7hU2s8flBvS4pGMFFmQAsKKoS gEnATSwN37UQQ== Received: from netfilter.org (mail-agni [217.70.190.124]) by mail.netfilter.org (Postfix) with UTF8SMTPSA id 770C16017D; Wed, 9 Sep 2026 02:52:24 +0200 (CEST) Date: Wed, 9 Sep 2026 02:52:22 +0200 From: Pablo Neira Ayuso To: Zihan Xi Cc: Florian Westphal , Phil Sutter , "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , netfilter-devel@vger.kernel.org, coreteam@netfilter.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH nf 0/1] netfilter: x_tables: avoid holding mutex over faultable user copies Message-ID: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: On Tue, Sep 01, 2026 at 01:47:53PM +0000, Zihan Xi wrote: [...] > Reproducer: > > The following files must be saved with these exact names in one directory. > The commands below build all helpers and run the FUSE/user-namespace path. > The FUSE helper binary is named poc-userns-trig so the hung-task comm > matches the crash log. The captured panic is hung_task after that task > blocked for more than 10 seconds, and then khungtaskd panics because > hung_task_panic=1. A 10-second timeout alone only warns; it does not > panic. The tested guest enabled panic on the kernel command line with > hung_task_panic=1 hung_task_timeout_secs=10 > hung_task_check_interval_secs=10 panic=-1. poc.sh, poc-userns-trig and > poc.c also write these sysctls when they are writable: > > echo 10 > /proc/sys/kernel/hung_task_timeout_secs > echo 10 > /proc/sys/kernel/hung_task_check_interval_secs > echo 10 > /proc/sys/kernel/hung_task_warnings > echo 1 > /proc/sys/kernel/hung_task_panic This configuration does not look sensible to me.