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=-9.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 602BFC49ED9 for ; Tue, 10 Sep 2019 20:03:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3232E2168B for ; Tue, 10 Sep 2019 20:03:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="ApS9vCdQ"; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="Rp9wm8Yc" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725978AbfIJUDW (ORCPT ); Tue, 10 Sep 2019 16:03:22 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:36388 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725797AbfIJUDW (ORCPT ); Tue, 10 Sep 2019 16:03:22 -0400 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id 459066050D; Tue, 10 Sep 2019 20:03:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1568145801; bh=rTk2AboRcVI9XJV9xBDexev/F1Ui4aP17kbTJ96p26o=; h=From:To:Cc:Subject:Date:From; b=ApS9vCdQGO0c8MjsixY2DVkSagQ/8IbMy7BgBvRjhMAZMSFvBtOytvqVhBkHYE/Jz sLw2NkuKolyj7+5MljQYc4GTq1pdvVwGA+CwAVXgyeDohkLFWyasoSxfykab9dxeUi 9jBA3E+QZiqhQT+JNN38h0TwF+nmcu8Pioh+M/h4= Received: from subashab-lnx.qualcomm.com (unknown [129.46.15.92]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: subashab@codeaurora.org) by smtp.codeaurora.org (Postfix) with ESMTPSA id 04F826050D; Tue, 10 Sep 2019 20:03:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1568145800; bh=rTk2AboRcVI9XJV9xBDexev/F1Ui4aP17kbTJ96p26o=; h=From:To:Cc:Subject:Date:From; b=Rp9wm8YcewZjEEzZer2XmPBTw1nQCd+a2aJzRJFv6MCgM2OvBSO/HwWyEj6N6Z+9d FqS+V/tSFCIH2SArAuk5XrkbqAP98iy3ayVwIOKqy8btjjf3BRFIFdVDGjmB3pGaUA o5TOPfkQ1vXP9WqwiKHxkQiqBUTEFrPvh6ZVWS0c= DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 04F826050D Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=subashab@codeaurora.org From: Subash Abhinov Kasiviswanathan To: dlezcano@fr.ibm.com, eric.dumazet@gmail.com, davem@davemloft.net, netdev@vger.kernel.org Cc: Subash Abhinov Kasiviswanathan , Sean Tranchetti Subject: [PATCH net] net: Fix null de-reference of device refcount Date: Tue, 10 Sep 2019 14:02:57 -0600 Message-Id: <1568145777-29480-1-git-send-email-subashab@codeaurora.org> X-Mailer: git-send-email 1.9.1 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org In event of failure during register_netdevice, free_netdev is invoked immediately. free_netdev assumes that all the netdevice refcounts have been dropped prior to it being called and as a result frees and clears out the refcount pointer. However, this is not necessarily true as some of the operations in the NETDEV_UNREGISTER notifier handlers queue RCU callbacks for invocation after a grace period. The IPv4 callback in_dev_rcu_put tries to access the refcount after free_netdev is called which leads to a null de-reference- 44837.761523: <6> Unable to handle kernel paging request at virtual address 0000004a88287000 44837.761651: <2> pc : in_dev_finish_destroy+0x4c/0xc8 44837.761654: <2> lr : in_dev_finish_destroy+0x2c/0xc8 44837.762393: <2> Call trace: 44837.762398: <2> in_dev_finish_destroy+0x4c/0xc8 44837.762404: <2> in_dev_rcu_put+0x24/0x30 44837.762412: <2> rcu_nocb_kthread+0x43c/0x468 44837.762418: <2> kthread+0x118/0x128 44837.762424: <2> ret_from_fork+0x10/0x1c Fix this by waiting for the completion of the call_rcu() in case of register_netdevice errors. Fixes: 93ee31f14f6f ("[NET]: Fix free_netdev on register_netdev failure.") Cc: Sean Tranchetti Signed-off-by: Subash Abhinov Kasiviswanathan --- net/core/dev.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/core/dev.c b/net/core/dev.c index 49589ed..c7463c9 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -8796,6 +8796,8 @@ int register_netdevice(struct net_device *dev) ret = notifier_to_errno(ret); if (ret) { rollback_registered(dev); + rcu_barrier(); + dev->reg_state = NETREG_UNREGISTERED; } /* -- 1.9.1