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 X-Spam-Level: X-Spam-Status: No, score=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 81A18C433ED for ; Thu, 20 May 2021 11:44:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5FD0D6105A for ; Thu, 20 May 2021 11:44:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242042AbhETLqP (ORCPT ); Thu, 20 May 2021 07:46:15 -0400 Received: from mail.kernel.org ([198.145.29.99]:44012 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241520AbhETLYo (ORCPT ); Thu, 20 May 2021 07:24:44 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 008BF61968; Thu, 20 May 2021 10:12:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1621505566; bh=HKJcPFWEfWxSCjuhXD9zo4ge2BXyQcW4uNDhnkX1zVY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=B2GjwxSOMdTSbuJxED4IJIt7K9KIoMV7XbGfR9iZk4EEj+Te4LaRyPdDH0SkG9mOF UA4DSXIUtUbvvBXqiFrkuB2nLP6YX4k8dzrUxPA3GIJiekhs5JduMFzV33vQ97OCUt OguqsVEGH4G/49d+htYB8GNsP53ADcv8BCREksVw= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eric Dumazet , syzbot , "David S. Miller" Subject: [PATCH 4.4 186/190] sit: proper dev_{hold|put} in ndo_[un]init methods Date: Thu, 20 May 2021 11:24:10 +0200 Message-Id: <20210520092108.317235983@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210520092102.149300807@linuxfoundation.org> References: <20210520092102.149300807@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: Eric Dumazet commit 6289a98f0817a4a457750d6345e754838eae9439 upstream. After adopting CONFIG_PCPU_DEV_REFCNT=n option, syzbot was able to trigger a warning [1] Issue here is that: - all dev_put() should be paired with a corresponding prior dev_hold(). - A driver doing a dev_put() in its ndo_uninit() MUST also do a dev_hold() in its ndo_init(), only when ndo_init() is returning 0. Otherwise, register_netdevice() would call ndo_uninit() in its error path and release a refcount too soon. Fixes: 919067cc845f ("net: add CONFIG_PCPU_DEV_REFCNT") Signed-off-by: Eric Dumazet Reported-by: syzbot Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv6/sit.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) --- a/net/ipv6/sit.c +++ b/net/ipv6/sit.c @@ -209,8 +209,6 @@ static int ipip6_tunnel_create(struct ne dev->rtnl_link_ops = &sit_link_ops; - dev_hold(dev); - ipip6_tunnel_link(sitn, t); return 0; @@ -1399,7 +1397,7 @@ static int ipip6_tunnel_init(struct net_ dev->tstats = NULL; return err; } - + dev_hold(dev); return 0; }