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=-9.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 EE4F6C169C4 for ; Thu, 31 Jan 2019 21:06:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AB940218FC for ; Thu, 31 Jan 2019 21:06:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="LNY3xqCX" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729037AbfAaVF7 (ORCPT ); Thu, 31 Jan 2019 16:05:59 -0500 Received: from mail-pl1-f194.google.com ([209.85.214.194]:42963 "EHLO mail-pl1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726678AbfAaVF7 (ORCPT ); Thu, 31 Jan 2019 16:05:59 -0500 Received: by mail-pl1-f194.google.com with SMTP id y1so2028582plp.9 for ; Thu, 31 Jan 2019 13:05:58 -0800 (PST) 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=V0L4BTlwBWPrShoCo8K2WOiDTT2FILVxedW1Ey6GbVw=; b=LNY3xqCXHmeeAjcy5IfkUYLWQUaY/Ic/c0NXHiTpaFqhryFZDBMP7Gq18YT7Mu8FK2 Pt7i3cAlCrtq6QxVH1HQIlG3P7fIjP2Ys6h0zmJuE44h7mcFclUOaEKfPqQ+duBxbR+1 YWtPAA1ecEfFt9mireR3pGqV1fnuJ2pPy4X1ck+L+iw434z74jfFx8kfaVeR50L2F0k4 z73CT7Fo8fWR54j15xdckHrtQx8PbhQqS7BF0zlmRvFV7wq4kaal8nnFxFbXPMOVGhUW NLmIZrJNirszQc1XmquEYTjQ4Qj2WvU3OEq3O0aiysBR8rmz9LvHZSCwyFs2lHbY0CJG F6kA== 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=V0L4BTlwBWPrShoCo8K2WOiDTT2FILVxedW1Ey6GbVw=; b=SF361UJ5pp9+m9EPpBQ+8YrEnuYHski+2mXAwRPISkzgMXQizeoQG6RfCzBTl09922 fXEbwYt3Fjq8wspPoSFc8ny+zIoxtbFOViitxO1K6wPltfX/AIVWLUGlH2nEDj7pbQY0 fCHpNvG1ndWttwQgvbAhkFs4DsAdixosXltLXIhS7lCbEWTz/t7XAnYvQhw0ucJdtgIJ TCuOCKFKx3ZyiUQYg6fkWsJ95SkKDTK/4o2PJPjbzpHtDbp4s5XgK8BNKESkbcF49IIp P5oCxKCwiG5GHpR9dcKKDzx3eG7l512sMkmqng8OqTVNrkEl7TBtvD6dK0utIrlg5kkT w2Dw== X-Gm-Message-State: AJcUukeYN+HYq+igVf6AujkjqcOiBgE0mo8gUzw6mjC0A+FIrwQupo1Z 2bGHjPq3nHVZO8sRmkWVflgwHgNm X-Google-Smtp-Source: ALg8bN6VvFnq7d1MfB7O8sz6tOXMVp3ts8qVoFktEc/6YvXSZaNDYVoPSz1eORO5/2sSD/bWTTf9TA== X-Received: by 2002:a17:902:6b46:: with SMTP id g6mr36390131plt.21.1548968757851; Thu, 31 Jan 2019 13:05:57 -0800 (PST) Received: from tw-172-25-17-123.office.twttr.net ([8.25.197.27]) by smtp.gmail.com with ESMTPSA id 62sm5950194pgc.61.2019.01.31.13.05.56 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 31 Jan 2019 13:05:56 -0800 (PST) From: Cong Wang To: netdev@vger.kernel.org Cc: Cong Wang , syzbot+e9aebef558e3ed673934@syzkaller.appspotmail.com, Steffen Klassert Subject: [Patch net v2] xfrm: destroy xfrm_state synchronously on net exit path Date: Thu, 31 Jan 2019 13:05:49 -0800 Message-Id: <20190131210549.3114-1-xiyou.wangcong@gmail.com> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org xfrm_state_put() moves struct xfrm_state to the GC list and schedules the GC work to clean it up. On net exit call path, xfrm_state_flush() is called to clean up and xfrm_flush_gc() is called to wait for the GC work to complete before exit. However, this doesn't work because one of the ->destructor(), ipcomp_destroy(), schedules the same GC work again inside the GC work. It is hard to wait for such a nested async callback. This is also why syzbot still reports the following warning: WARNING: CPU: 1 PID: 33 at net/ipv6/xfrm6_tunnel.c:351 xfrm6_tunnel_net_exit+0x2cb/0x500 net/ipv6/xfrm6_tunnel.c:351 ... ops_exit_list.isra.0+0xb0/0x160 net/core/net_namespace.c:153 cleanup_net+0x51d/0xb10 net/core/net_namespace.c:551 process_one_work+0xd0c/0x1ce0 kernel/workqueue.c:2153 worker_thread+0x143/0x14a0 kernel/workqueue.c:2296 kthread+0x357/0x430 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352 In fact, it is perfectly fine to bypass GC and destroy xfrm_state synchronously on net exit call path, because it is in process context and doesn't need a work struct to do any blocking work. This patch introduces xfrm_state_put_sync() which simply bypasses GC, and lets its callers to decide whether to use this synchronous version. On net exit path, xfrm_state_fini() and xfrm6_tunnel_net_exit() use it. And, as ipcomp_destroy() itself is blocking, it can use xfrm_state_put_sync() directly too. Also rename xfrm_state_gc_destroy() to ___xfrm_state_destroy() to reflect this change. Fixes: b48c05ab5d32 ("xfrm: Fix warning in xfrm6_tunnel_net_exit.") Reported-and-tested-by: syzbot+e9aebef558e3ed673934@syzkaller.appspotmail.com Cc: Steffen Klassert Signed-off-by: Cong Wang --- include/net/xfrm.h | 12 +++++++++--- net/ipv6/xfrm6_tunnel.c | 2 +- net/key/af_key.c | 2 +- net/xfrm/xfrm_state.c | 30 +++++++++++++++++++----------- net/xfrm/xfrm_user.c | 2 +- 5 files changed, 31 insertions(+), 17 deletions(-) diff --git a/include/net/xfrm.h b/include/net/xfrm.h index 7298a53b9702..85386becbaea 100644 --- a/include/net/xfrm.h +++ b/include/net/xfrm.h @@ -853,7 +853,7 @@ static inline void xfrm_pols_put(struct xfrm_policy **pols, int npols) xfrm_pol_put(pols[i]); } -void __xfrm_state_destroy(struct xfrm_state *); +void __xfrm_state_destroy(struct xfrm_state *, bool); static inline void __xfrm_state_put(struct xfrm_state *x) { @@ -863,7 +863,13 @@ static inline void __xfrm_state_put(struct xfrm_state *x) static inline void xfrm_state_put(struct xfrm_state *x) { if (refcount_dec_and_test(&x->refcnt)) - __xfrm_state_destroy(x); + __xfrm_state_destroy(x, false); +} + +static inline void xfrm_state_put_sync(struct xfrm_state *x) +{ + if (refcount_dec_and_test(&x->refcnt)) + __xfrm_state_destroy(x, true); } static inline void xfrm_state_hold(struct xfrm_state *x) @@ -1590,7 +1596,7 @@ struct xfrmk_spdinfo { struct xfrm_state *xfrm_find_acq_byseq(struct net *net, u32 mark, u32 seq); int xfrm_state_delete(struct xfrm_state *x); -int xfrm_state_flush(struct net *net, u8 proto, bool task_valid); +int xfrm_state_flush(struct net *net, u8 proto, bool task_valid, bool sync); int xfrm_dev_state_flush(struct net *net, struct net_device *dev, bool task_valid); void xfrm_sad_getinfo(struct net *net, struct xfrmk_sadinfo *si); void xfrm_spd_getinfo(struct net *net, struct xfrmk_spdinfo *si); diff --git a/net/ipv6/xfrm6_tunnel.c b/net/ipv6/xfrm6_tunnel.c index f5b4febeaa25..bc65db782bfb 100644 --- a/net/ipv6/xfrm6_tunnel.c +++ b/net/ipv6/xfrm6_tunnel.c @@ -344,8 +344,8 @@ static void __net_exit xfrm6_tunnel_net_exit(struct net *net) struct xfrm6_tunnel_net *xfrm6_tn = xfrm6_tunnel_pernet(net); unsigned int i; - xfrm_state_flush(net, IPSEC_PROTO_ANY, false); xfrm_flush_gc(); + xfrm_state_flush(net, IPSEC_PROTO_ANY, false, true); for (i = 0; i < XFRM6_TUNNEL_SPI_BYADDR_HSIZE; i++) WARN_ON_ONCE(!hlist_empty(&xfrm6_tn->spi_byaddr[i])); diff --git a/net/key/af_key.c b/net/key/af_key.c index 655c787f9d54..637030f43b67 100644 --- a/net/key/af_key.c +++ b/net/key/af_key.c @@ -1783,7 +1783,7 @@ static int pfkey_flush(struct sock *sk, struct sk_buff *skb, const struct sadb_m if (proto == 0) return -EINVAL; - err = xfrm_state_flush(net, proto, true); + err = xfrm_state_flush(net, proto, true, false); err2 = unicast_flush_resp(sk, hdr); if (err || err2) { if (err == -ESRCH) /* empty table - go quietly */ diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c index 23c92891758a..1bb971f46fc6 100644 --- a/net/xfrm/xfrm_state.c +++ b/net/xfrm/xfrm_state.c @@ -432,7 +432,7 @@ void xfrm_state_free(struct xfrm_state *x) } EXPORT_SYMBOL(xfrm_state_free); -static void xfrm_state_gc_destroy(struct xfrm_state *x) +static void ___xfrm_state_destroy(struct xfrm_state *x) { tasklet_hrtimer_cancel(&x->mtimer); del_timer_sync(&x->rtimer); @@ -474,7 +474,7 @@ static void xfrm_state_gc_task(struct work_struct *work) synchronize_rcu(); hlist_for_each_entry_safe(x, tmp, &gc_list, gclist) - xfrm_state_gc_destroy(x); + ___xfrm_state_destroy(x); } static enum hrtimer_restart xfrm_timer_handler(struct hrtimer *me) @@ -598,14 +598,19 @@ struct xfrm_state *xfrm_state_alloc(struct net *net) } EXPORT_SYMBOL(xfrm_state_alloc); -void __xfrm_state_destroy(struct xfrm_state *x) +void __xfrm_state_destroy(struct xfrm_state *x, bool sync) { WARN_ON(x->km.state != XFRM_STATE_DEAD); - spin_lock_bh(&xfrm_state_gc_lock); - hlist_add_head(&x->gclist, &xfrm_state_gc_list); - spin_unlock_bh(&xfrm_state_gc_lock); - schedule_work(&xfrm_state_gc_work); + if (sync) { + synchronize_rcu(); + ___xfrm_state_destroy(x); + } else { + spin_lock_bh(&xfrm_state_gc_lock); + hlist_add_head(&x->gclist, &xfrm_state_gc_list); + spin_unlock_bh(&xfrm_state_gc_lock); + schedule_work(&xfrm_state_gc_work); + } } EXPORT_SYMBOL(__xfrm_state_destroy); @@ -708,7 +713,7 @@ xfrm_dev_state_flush_secctx_check(struct net *net, struct net_device *dev, bool } #endif -int xfrm_state_flush(struct net *net, u8 proto, bool task_valid) +int xfrm_state_flush(struct net *net, u8 proto, bool task_valid, bool sync) { int i, err = 0, cnt = 0; @@ -730,7 +735,10 @@ int xfrm_state_flush(struct net *net, u8 proto, bool task_valid) err = xfrm_state_delete(x); xfrm_audit_state_delete(x, err ? 0 : 1, task_valid); - xfrm_state_put(x); + if (sync) + xfrm_state_put_sync(x); + else + xfrm_state_put(x); if (!err) cnt++; @@ -2215,7 +2223,7 @@ void xfrm_state_delete_tunnel(struct xfrm_state *x) if (atomic_read(&t->tunnel_users) == 2) xfrm_state_delete(t); atomic_dec(&t->tunnel_users); - xfrm_state_put(t); + xfrm_state_put_sync(t); x->tunnel = NULL; } } @@ -2375,8 +2383,8 @@ void xfrm_state_fini(struct net *net) unsigned int sz; flush_work(&net->xfrm.state_hash_work); - xfrm_state_flush(net, IPSEC_PROTO_ANY, false); flush_work(&xfrm_state_gc_work); + xfrm_state_flush(net, IPSEC_PROTO_ANY, false, true); WARN_ON(!list_empty(&net->xfrm.state_all)); diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c index c6d26afcf89d..a131f9ff979e 100644 --- a/net/xfrm/xfrm_user.c +++ b/net/xfrm/xfrm_user.c @@ -1932,7 +1932,7 @@ static int xfrm_flush_sa(struct sk_buff *skb, struct nlmsghdr *nlh, struct xfrm_usersa_flush *p = nlmsg_data(nlh); int err; - err = xfrm_state_flush(net, p->proto, true); + err = xfrm_state_flush(net, p->proto, true, false); if (err) { if (err == -ESRCH) /* empty table */ return 0; -- 2.20.1