From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from ganesha.gnumonks.org (ganesha.gnumonks.org [213.95.27.120]) (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 9D9261822E2; Thu, 4 Jul 2024 13:51:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.95.27.120 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720101111; cv=none; b=RTXH8pUGNi3L+Q+CGFe+7zHlm/KqhQTiS0VCNXaFa4b7vLJEEkQREBubKikXR6GUjK7GtDOob5Vv5cSEZBjXG2sNZJTVNM+LE5+UDcxDCPcugiB09JBbT14HJargmCfY8XQjF/UkksbQ+fO1HhVJyTPymyzIutr5hRC3ycu6C4s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720101111; c=relaxed/simple; bh=j7y3SaNZOdZ/qlSujb8S0Jm/YN/yBFAlgHfB7bnQva4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=iYJYXGfVF4yL4UAr+DWvkVDfvIh1Grr9LkYnWTHYx4vaHqP63ZmfywIsQdGomfGevvL2jgD0UTMlIFUCZ/v0T01X0GRngxxYnDUl5FenW5m3nixMfCIezTI5HbKOtoPGeqCL6Qsqq1fm2K9OJCdFZ8EGAf437Sv3a9UeOoEZ0l4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=netfilter.org; spf=pass smtp.mailfrom=gnumonks.org; arc=none smtp.client-ip=213.95.27.120 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=gnumonks.org Received: from [78.30.37.63] (port=48078 helo=gnumonks.org) by ganesha.gnumonks.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1sPMWm-004unV-LC; Thu, 04 Jul 2024 15:29:39 +0200 Date: Thu, 4 Jul 2024 15:29:34 +0200 From: Pablo Neira Ayuso To: Paolo Abeni Cc: netfilter-devel@vger.kernel.org, davem@davemloft.net, netdev@vger.kernel.org, kuba@kernel.org, edumazet@google.com, fw@strlen.de Subject: Re: [PATCH net 1/1] netfilter: nf_tables: unconditionally flush pending work before notifier Message-ID: References: <20240703223304.1455-1-pablo@netfilter.org> <20240703223304.1455-2-pablo@netfilter.org> Precedence: bulk X-Mailing-List: netfilter-devel@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: X-Spam-Score: -1.8 (-) On Thu, Jul 04, 2024 at 03:24:17PM +0200, Paolo Abeni wrote: > Hi, > > On Thu, 2024-07-04 at 00:33 +0200, Pablo Neira Ayuso wrote: > > From: Florian Westphal > > > > syzbot reports: > > > > KASAN: slab-uaf in nft_ctx_update include/net/netfilter/nf_tables.h:1831 > > KASAN: slab-uaf in nft_commit_release net/netfilter/nf_tables_api.c:9530 > > KASAN: slab-uaf int nf_tables_trans_destroy_work+0x152b/0x1750 net/netfilter/nf_tables_api.c:9597 > > Read of size 2 at addr ffff88802b0051c4 by task kworker/1:1/45 > > [..] > > Workqueue: events nf_tables_trans_destroy_work > > Call Trace: > > nft_ctx_update include/net/netfilter/nf_tables.h:1831 [inline] > > nft_commit_release net/netfilter/nf_tables_api.c:9530 [inline] > > nf_tables_trans_destroy_work+0x152b/0x1750 net/netfilter/nf_tables_api.c:9597 > > > > Problem is that the notifier does a conditional flush, but its possible > > that the table-to-be-removed is still referenced by transactions being > > processed by the worker, so we need to flush unconditionally. > > > > We could make the flush_work depend on whether we found a table to delete > > in nf-next to avoid the flush for most cases. > > > > AFAICS this problem is only exposed in nf-next, with > > commit e169285f8c56 ("netfilter: nf_tables: do not store nft_ctx in transaction objects"), > > with this commit applied there is an unconditional fetch of > > table->family which is whats triggering the above splat. > > > > Fixes: 2c9f0293280e ("netfilter: nf_tables: flush pending destroy work before netlink notifier") > > Reported-and-tested-by: syzbot+4fd66a69358fc15ae2ad@syzkaller.appspotmail.com > > Closes: https://syzkaller.appspot.com/bug?extid=4fd66a69358fc15ae2ad > > Signed-off-by: Florian Westphal > > Signed-off-by: Pablo Neira Ayuso > > --- > > net/netfilter/nf_tables_api.c | 3 +-- > > 1 file changed, 1 insertion(+), 2 deletions(-) > > > > diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c > > index e8dcf41d360d..081c08536d0f 100644 > > --- a/net/netfilter/nf_tables_api.c > > +++ b/net/netfilter/nf_tables_api.c > > @@ -11483,8 +11483,7 @@ static int nft_rcv_nl_event(struct notifier_block *this, unsigned long event, > > > > gc_seq = nft_gc_seq_begin(nft_net); > > > > - if (!list_empty(&nf_tables_destroy_list)) > > - nf_tables_trans_destroy_flush_work(); > > + nf_tables_trans_destroy_flush_work(); > > again: > > list_for_each_entry(table, &nft_net->tables, list) { > > if (nft_table_has_owner(table) && > > It look like there is still some discussion around this patch, but I > guess we can still take it and in the worst case scenario a follow-up > will surface, right? Let's do that. Thanks.