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 EF89BC43334 for ; Tue, 5 Jul 2022 12:03:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233357AbiGEMDJ (ORCPT ); Tue, 5 Jul 2022 08:03:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43556 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233453AbiGEMCq (ORCPT ); Tue, 5 Jul 2022 08:02:46 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 61D1C17E21; Tue, 5 Jul 2022 05:02:45 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 10B37B817D3; Tue, 5 Jul 2022 12:02:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 74C28C341C7; Tue, 5 Jul 2022 12:02:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1657022562; bh=RBN1VrK3jAHNYDEBxvR5VsJAYA7eBYhPYQO6FEJg6Ik=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=mLsRrjUX5CMWqKo3IT+65JxshvcWUC1dtjvxqbpVLiIAOeek0JHzjeZcbsghAHzvI IklF3/Ob5kg5aB50nGBePGTT1DDqUHVdkE9ayI/4bntTkxsUfI028kblSq7L7omgHR auQCBtjvK1qOE7i2V6eZFjiAkI/rP7XfyremAfr4= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot , Eric Dumazet , Jakub Kicinski Subject: [PATCH 4.19 21/33] net: tun: avoid disabling NAPI twice Date: Tue, 5 Jul 2022 13:58:13 +0200 Message-Id: <20220705115607.334949507@linuxfoundation.org> X-Mailer: git-send-email 2.37.0 In-Reply-To: <20220705115606.709817198@linuxfoundation.org> References: <20220705115606.709817198@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Jakub Kicinski commit ff1fa2081d173b01cebe2fbf0a2d0f1cee9ce4b5 upstream. Eric reports that syzbot made short work out of my speculative fix. Indeed when queue gets detached its tfile->tun remains, so we would try to stop NAPI twice with a detach(), close() sequence. Alternative fix would be to move tun_napi_disable() to tun_detach_all() and let the NAPI run after the queue has been detached. Fixes: a8fc8cb5692a ("net: tun: stop NAPI when detaching queues") Reported-by: syzbot Reported-by: Eric Dumazet Reviewed-by: Eric Dumazet Link: https://lore.kernel.org/r/20220629181911.372047-1-kuba@kernel.org Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- drivers/net/tun.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -710,7 +710,8 @@ static void __tun_detach(struct tun_file tun = rtnl_dereference(tfile->tun); if (tun && clean) { - tun_napi_disable(tfile); + if (!tfile->detached) + tun_napi_disable(tfile); tun_napi_del(tfile); }