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 AF7BAC43334 for ; Tue, 5 Jul 2022 12:11:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235051AbiGEMLA (ORCPT ); Tue, 5 Jul 2022 08:11:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45648 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233346AbiGEMGE (ORCPT ); Tue, 5 Jul 2022 08:06:04 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2705C18E35; Tue, 5 Jul 2022 05:05:26 -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 C87C4B817C7; Tue, 5 Jul 2022 12:05:24 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 397AFC341C7; Tue, 5 Jul 2022 12:05:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1657022723; bh=0bluImkZpCzaYQZjKlD4t1mEqrwXpo6gaWJYtmqZ4uM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tBKthNQ22j1qUhvSjxw52n96R/yLWrJxy7pOuBhTsfrBZIl9lQADAiFqjXGi34Qmi n0IW0CVMpS6/0DiFukHYr8YdCI4oPvrFLO7XchYOonj9A9jDLQkmAUNMtnDg3MdJCg paWNYgoM8JDU1vN38iEUD3woZqDb7VjxM1gtzXcI= 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 5.4 28/58] net: tun: avoid disabling NAPI twice Date: Tue, 5 Jul 2022 13:58:04 +0200 Message-Id: <20220705115611.074797102@linuxfoundation.org> X-Mailer: git-send-email 2.37.0 In-Reply-To: <20220705115610.236040773@linuxfoundation.org> References: <20220705115610.236040773@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: linux-kernel@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 @@ -696,7 +696,8 @@ 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); }