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, URIBL_BLOCKED,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 49D79C43619 for ; Mon, 17 May 2021 14:48:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2C41761403 for ; Mon, 17 May 2021 14:48:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242192AbhEQOuE (ORCPT ); Mon, 17 May 2021 10:50:04 -0400 Received: from mail.kernel.org ([198.145.29.99]:54302 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241226AbhEQOnX (ORCPT ); Mon, 17 May 2021 10:43:23 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 56D666135B; Mon, 17 May 2021 14:20:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1621261218; bh=oIhCG2ho6VV6y69Wpbc6slEAsiC9IjKPO5oQ593WBJU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=mbuDjgglTuFv4LVsMXBORVd/lB7dSuQQlb+3QubQ4X4cYdKy6zbFtLzB71xh1oxC9 m1XNtY5op+hdypqM9ZkaAXc5RpiipIxFuwfcU9Nteedayo4IlCGeAhhjqUqbB48We2 KiI56WPDnM96yDBEVJGpWplJPIF8d+juP21W73Sk= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eric Dumazet , "David S. Miller" , Sasha Levin Subject: [PATCH 5.4 020/141] ip6_vti: proper dev_{hold|put} in ndo_[un]init methods Date: Mon, 17 May 2021 16:01:12 +0200 Message-Id: <20210517140243.443931506@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210517140242.729269392@linuxfoundation.org> References: <20210517140242.729269392@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 [ Upstream commit 40cb881b5aaa0b69a7d93dec8440d5c62dae299f ] 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. Therefore, we need to move dev_hold() call from vti6_tnl_create2() to vti6_dev_init_gen() [1] WARNING: CPU: 0 PID: 15951 at lib/refcount.c:31 refcount_warn_saturate+0xbf/0x1e0 lib/refcount.c:31 Modules linked in: CPU: 0 PID: 15951 Comm: syz-executor.3 Not tainted 5.12.0-rc4-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:refcount_warn_saturate+0xbf/0x1e0 lib/refcount.c:31 Code: 1d 6a 5a e8 09 31 ff 89 de e8 8d 1a ab fd 84 db 75 e0 e8 d4 13 ab fd 48 c7 c7 a0 e1 c1 89 c6 05 4a 5a e8 09 01 e8 2e 36 fb 04 <0f> 0b eb c4 e8 b8 13 ab fd 0f b6 1d 39 5a e8 09 31 ff 89 de e8 58 RSP: 0018:ffffc90001eaef28 EFLAGS: 00010282 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000040000 RSI: ffffffff815c51f5 RDI: fffff520003d5dd7 RBP: 0000000000000004 R08: 0000000000000000 R09: 0000000000000000 R10: ffffffff815bdf8e R11: 0000000000000000 R12: ffff88801bb1c568 R13: ffff88801f69e800 R14: 00000000ffffffff R15: ffff888050889d40 FS: 00007fc79314e700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f1c1ff47108 CR3: 0000000020fd5000 CR4: 00000000001506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __refcount_dec include/linux/refcount.h:344 [inline] refcount_dec include/linux/refcount.h:359 [inline] dev_put include/linux/netdevice.h:4135 [inline] vti6_dev_uninit+0x31a/0x360 net/ipv6/ip6_vti.c:297 register_netdevice+0xadf/0x1500 net/core/dev.c:10308 vti6_tnl_create2+0x1b5/0x400 net/ipv6/ip6_vti.c:190 vti6_newlink+0x9d/0xd0 net/ipv6/ip6_vti.c:1020 __rtnl_newlink+0x1062/0x1710 net/core/rtnetlink.c:3443 rtnl_newlink+0x64/0xa0 net/core/rtnetlink.c:3491 rtnetlink_rcv_msg+0x44e/0xad0 net/core/rtnetlink.c:5553 netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2502 netlink_unicast_kernel net/netlink/af_netlink.c:1312 [inline] netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1338 netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1927 sock_sendmsg_nosec net/socket.c:654 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:674 ____sys_sendmsg+0x331/0x810 net/socket.c:2350 ___sys_sendmsg+0xf3/0x170 net/socket.c:2404 __sys_sendmmsg+0x195/0x470 net/socket.c:2490 __do_sys_sendmmsg net/socket.c:2519 [inline] __se_sys_sendmmsg net/socket.c:2516 [inline] __x64_sys_sendmmsg+0x99/0x100 net/socket.c:2516 Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/ipv6/ip6_vti.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/ipv6/ip6_vti.c b/net/ipv6/ip6_vti.c index cc6180e08a4f..01ddb0f70c57 100644 --- a/net/ipv6/ip6_vti.c +++ b/net/ipv6/ip6_vti.c @@ -192,7 +192,6 @@ static int vti6_tnl_create2(struct net_device *dev) strcpy(t->parms.name, dev->name); - dev_hold(dev); vti6_tnl_link(ip6n, t); return 0; @@ -921,6 +920,7 @@ static inline int vti6_dev_init_gen(struct net_device *dev) dev->tstats = netdev_alloc_pcpu_stats(struct pcpu_sw_netstats); if (!dev->tstats) return -ENOMEM; + dev_hold(dev); return 0; } -- 2.30.2