From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DA3C0C433F5 for ; Wed, 18 May 2022 17:51:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241132AbiERRv2 (ORCPT ); Wed, 18 May 2022 13:51:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60196 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241155AbiERRv0 (ORCPT ); Wed, 18 May 2022 13:51:26 -0400 Received: from mail.netfilter.org (mail.netfilter.org [217.70.188.207]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 9DD563151E for ; Wed, 18 May 2022 10:51:23 -0700 (PDT) Date: Wed, 18 May 2022 19:51:18 +0200 From: Pablo Neira Ayuso To: Florian Westphal Cc: netfilter-devel@vger.kernel.org, fasnacht@protonmail.ch Subject: Re: [PATCH nf,v2] netfilter: nf_tables: disable bh to update per-cpu rnd_state Message-ID: References: <20220518160022.224294-1-pablo@netfilter.org> <20220518164621.GH4316@breakpoint.cc> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20220518164621.GH4316@breakpoint.cc> Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org On Wed, May 18, 2022 at 06:46:21PM +0200, Florian Westphal wrote: > Pablo Neira Ayuso wrote: > > bh might occur while updating per-cpu rnd_state from user context, > > ie. local_out path. > > > > [233241.951068] BUG: using smp_processor_id() in preemptible [00000000] code: nginx/2725 > > [233241.951220] caller is nft_ng_random_eval+0x24/0x54 [nft_numgen] > > [233241.951225] CPU: 2 PID: 2725 Comm: nginx Tainted: G OE 5.16.0-0.bpo.4-amd64 #1 Debian 5.16.12-1~bpo11+1 > > [233241.951227] Hardware name: Supermicro SYS-5039MC-H8TRF/X11SCD-F, BIOS 1.7 11/23/2021 > > [233241.951228] Call Trace: > > [233241.951231] > > [233241.951233] dump_stack_lvl+0x48/0x5e > > [233241.951236] check_preemption_disabled+0xde/0xe0 > > [233241.951239] nft_ng_random_eval+0x24/0x54 [nft_numgen] > > > > Fixes: 6b2faee0ca91 ("netfilter: nft_meta: place prandom handling in a helper") > > Fixes: 978d8f9055c3 ("netfilter: nft_numgen: add map lookups for numgen random operations") > > Signed-off-by: Pablo Neira Ayuso > > --- > > v2: disable/enable bh > > @Florian: your rand meta support is missing {disable,enable}_local_bh() > > I wonder if its better to just switch to get_random_u32() instead of prandom. Feel free to pick if you would like to send a v3.