From patchwork Mon Mar 29 19:12:54 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Dumazet X-Patchwork-Id: 12170873 X-Patchwork-Delegate: kuba@kernel.org 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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 CBD91C433C1 for ; Mon, 29 Mar 2021 19:13:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 91E2E61936 for ; Mon, 29 Mar 2021 19:13:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231665AbhC2TN0 (ORCPT ); Mon, 29 Mar 2021 15:13:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50424 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231799AbhC2TM6 (ORCPT ); Mon, 29 Mar 2021 15:12:58 -0400 Received: from mail-pj1-x102d.google.com (mail-pj1-x102d.google.com [IPv6:2607:f8b0:4864:20::102d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BC867C061574 for ; Mon, 29 Mar 2021 12:12:58 -0700 (PDT) Received: by mail-pj1-x102d.google.com with SMTP id kr3-20020a17090b4903b02900c096fc01deso6404271pjb.4 for ; Mon, 29 Mar 2021 12:12:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=h4fhbSE7DTIdgN26xFWwTxk5fBSRiGCSGdu+yOAmxXg=; b=V2QT+abceb12TOwfxGT8k+A0IjZfnX/nnORIk0NRRBlPpBNymw3tpmRBVlcu/lD9sP RSJnTNEH6LPoqm4BgVEbK/6yvbD21AuSdgeMC+qnYlrItdY3GqeQLK56uzXHUZC7Lgo/ ZIG1JIVXiBr/55KuoDjDLmubVM4Wx07+X+f5yDYI5Eu64dfPVisjhjDWHxNDg5hAqjQW XXpdOhtveLbgyDdO3JjkmwEfYD1E3gpwFI13kg53IBzQmxOmfjlwXtmgDZFGp0bTtnX0 krcmrQRduF7IOGvW4o+HChJPd0fzPp5Jd2QO0NuV0BMLzm7PsqN5IInonNA0JrbWcOA3 WZJg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=h4fhbSE7DTIdgN26xFWwTxk5fBSRiGCSGdu+yOAmxXg=; b=gTg+FMC8x3M6WOhwQrQ0hVL5xMcbsxx5Ch/aXdsCAz2r4HfPDXmr/jbBbKLkYLw8W6 leJkUR5gRO2Nl/KUzts2bqjEnwRxVZzgXbwt10dvjwJYvX9/z6w0q33Oa6TqMQElXOOb tgES+WVAhZHC7ZgRT9cpCV/NRv2Vo+sVWE+A+FE3LxR/kXx04OOLqtsWg8UtjNO7VBa6 FO6bcOMcdI4U/oy3SWPR4hdddK3midgm5PXuajEpgT43QcuKYn2tKx6l8P66egjlGQv5 QxSJc1htcOKKOzZcLzM7UYb5zJO0X02jgaJnowhWQqRJEG4fHyNrGabzcwk7Mrbsd0ta h2WQ== X-Gm-Message-State: AOAM532dkBsPv/8agZLMxUDTAFIqEIfMIUMQPTE7uhb9IEXCsLzUgkHN M45S7jYORoPAuU6Tpc/kAZM= X-Google-Smtp-Source: ABdhPJw+RU0O/F+PUtKyc5ieLBu8k0pnHBXbRdjoIFuMkHxtsNBChJXl48+IKe5dE1DWAkqAmeY4Kg== X-Received: by 2002:a17:90a:1b08:: with SMTP id q8mr546673pjq.203.1617045178295; Mon, 29 Mar 2021 12:12:58 -0700 (PDT) Received: from edumazet1.svl.corp.google.com ([2620:15c:2c4:201:78a0:7565:129d:828c]) by smtp.gmail.com with ESMTPSA id c128sm17753196pfc.76.2021.03.29.12.12.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 29 Mar 2021 12:12:57 -0700 (PDT) From: Eric Dumazet To: "David S . Miller" , Jakub Kicinski Cc: netdev , Eric Dumazet , Eric Dumazet Subject: [PATCH net-next] ip6_vti: proper dev_{hold|put} in ndo_[un]init methods Date: Mon, 29 Mar 2021 12:12:54 -0700 Message-Id: <20210329191254.137053-1-eric.dumazet@gmail.com> X-Mailer: git-send-email 2.31.0.291.g576ba9dcdaf-goog MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org From: Eric Dumazet 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 --- 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 f10e7a72ea6248e5ec1fbdb8b4e1c4e0e874cb96..a018afdb3e062c9e664d4ca424176a859f0a332c 100644 --- a/net/ipv6/ip6_vti.c +++ b/net/ipv6/ip6_vti.c @@ -193,7 +193,6 @@ 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; @@ -932,6 +931,7 @@ 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; }