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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5EEE6C4707F for ; Mon, 7 Feb 2022 11:49:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1379226AbiBGLjv (ORCPT ); Mon, 7 Feb 2022 06:39:51 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46420 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1386249AbiBGLeI (ORCPT ); Mon, 7 Feb 2022 06:34:08 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A5F5DC043181; Mon, 7 Feb 2022 03:34:06 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 642D6B80EBD; Mon, 7 Feb 2022 11:34:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8EFA6C004E1; Mon, 7 Feb 2022 11:34:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1644233644; bh=uDfKvlFIo9V9/gtSAHiZdG/PPB0gTl8EG/gwzeM/smU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=XaRPBxrQ9pNob+pedp846bUTHPTC/XBmVb6jGXg93UjfBnDVxA5UuSd4ONCU1cvZc 5To4dZgkjDr0HqOApByxgIqzxaSMHYWvvhi538mCTdnSvv8fYsCSqaHBAOUdGk+dN/ 3fvZHsL6aQdxeJor7tQXtdJpsS3CqYzYTJUjdL+U= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+5239d0e1778a500d477a@syzkaller.appspotmail.com, Daniel Borkmann , Eric Dumazet , Roopa Prabhu , David Ahern , Jakub Kicinski Subject: [PATCH 5.16 076/126] net, neigh: Do not trigger immediate probes on NUD_FAILED from neigh_managed_work Date: Mon, 7 Feb 2022 12:06:47 +0100 Message-Id: <20220207103806.731818986@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220207103804.053675072@linuxfoundation.org> References: <20220207103804.053675072@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: stable@vger.kernel.org From: Daniel Borkmann commit 4a81f6da9cb2d1ef911131a6fd8bd15cb61fc772 upstream. syzkaller was able to trigger a deadlock for NTF_MANAGED entries [0]: kworker/0:16/14617 is trying to acquire lock: ffffffff8d4dd370 (&tbl->lock){++-.}-{2:2}, at: ___neigh_create+0x9e1/0x2990 net/core/neighbour.c:652 [...] but task is already holding lock: ffffffff8d4dd370 (&tbl->lock){++-.}-{2:2}, at: neigh_managed_work+0x35/0x250 net/core/neighbour.c:1572 The neighbor entry turned to NUD_FAILED state, where __neigh_event_send() triggered an immediate probe as per commit cd28ca0a3dd1 ("neigh: reduce arp latency") via neigh_probe() given table lock was held. One option to fix this situation is to defer the neigh_probe() back to the neigh_timer_handler() similarly as pre cd28ca0a3dd1. For the case of NTF_MANAGED, this deferral is acceptable given this only happens on actual failure state and regular / expected state is NUD_VALID with the entry already present. The fix adds a parameter to __neigh_event_send() in order to communicate whether immediate probe is allowed or disallowed. Existing call-sites of neigh_event_send() default as-is to immediate probe. However, the neigh_managed_work() disables it via use of neigh_event_send_probe(). [0] __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_deadlock_bug kernel/locking/lockdep.c:2956 [inline] check_deadlock kernel/locking/lockdep.c:2999 [inline] validate_chain kernel/locking/lockdep.c:3788 [inline] __lock_acquire.cold+0x149/0x3ab kernel/locking/lockdep.c:5027 lock_acquire kernel/locking/lockdep.c:5639 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5604 __raw_write_lock_bh include/linux/rwlock_api_smp.h:202 [inline] _raw_write_lock_bh+0x2f/0x40 kernel/locking/spinlock.c:334 ___neigh_create+0x9e1/0x2990 net/core/neighbour.c:652 ip6_finish_output2+0x1070/0x14f0 net/ipv6/ip6_output.c:123 __ip6_finish_output net/ipv6/ip6_output.c:191 [inline] __ip6_finish_output+0x61e/0xe90 net/ipv6/ip6_output.c:170 ip6_finish_output+0x32/0x200 net/ipv6/ip6_output.c:201 NF_HOOK_COND include/linux/netfilter.h:296 [inline] ip6_output+0x1e4/0x530 net/ipv6/ip6_output.c:224 dst_output include/net/dst.h:451 [inline] NF_HOOK include/linux/netfilter.h:307 [inline] ndisc_send_skb+0xa99/0x17f0 net/ipv6/ndisc.c:508 ndisc_send_ns+0x3a9/0x840 net/ipv6/ndisc.c:650 ndisc_solicit+0x2cd/0x4f0 net/ipv6/ndisc.c:742 neigh_probe+0xc2/0x110 net/core/neighbour.c:1040 __neigh_event_send+0x37d/0x1570 net/core/neighbour.c:1201 neigh_event_send include/net/neighbour.h:470 [inline] neigh_managed_work+0x162/0x250 net/core/neighbour.c:1574 process_one_work+0x9ac/0x1650 kernel/workqueue.c:2307 worker_thread+0x657/0x1110 kernel/workqueue.c:2454 kthread+0x2e9/0x3a0 kernel/kthread.c:377 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 Fixes: 7482e3841d52 ("net, neigh: Add NTF_MANAGED flag for managed neighbor entries") Reported-by: syzbot+5239d0e1778a500d477a@syzkaller.appspotmail.com Signed-off-by: Daniel Borkmann Cc: Eric Dumazet Cc: Roopa Prabhu Tested-by: syzbot+5239d0e1778a500d477a@syzkaller.appspotmail.com Reviewed-by: David Ahern Link: https://lore.kernel.org/r/20220201193942.5055-1-daniel@iogearbox.net Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- include/net/neighbour.h | 18 +++++++++++++----- net/core/neighbour.c | 18 ++++++++++++------ 2 files changed, 25 insertions(+), 11 deletions(-) --- a/include/net/neighbour.h +++ b/include/net/neighbour.h @@ -336,7 +336,8 @@ static inline struct neighbour *neigh_cr return __neigh_create(tbl, pkey, dev, true); } void neigh_destroy(struct neighbour *neigh); -int __neigh_event_send(struct neighbour *neigh, struct sk_buff *skb); +int __neigh_event_send(struct neighbour *neigh, struct sk_buff *skb, + const bool immediate_ok); int neigh_update(struct neighbour *neigh, const u8 *lladdr, u8 new, u32 flags, u32 nlmsg_pid); void __neigh_set_probe_once(struct neighbour *neigh); @@ -446,17 +447,24 @@ static inline struct neighbour * neigh_c #define neigh_hold(n) refcount_inc(&(n)->refcnt) -static inline int neigh_event_send(struct neighbour *neigh, struct sk_buff *skb) +static __always_inline int neigh_event_send_probe(struct neighbour *neigh, + struct sk_buff *skb, + const bool immediate_ok) { unsigned long now = jiffies; - + if (READ_ONCE(neigh->used) != now) WRITE_ONCE(neigh->used, now); - if (!(neigh->nud_state&(NUD_CONNECTED|NUD_DELAY|NUD_PROBE))) - return __neigh_event_send(neigh, skb); + if (!(neigh->nud_state & (NUD_CONNECTED | NUD_DELAY | NUD_PROBE))) + return __neigh_event_send(neigh, skb, immediate_ok); return 0; } +static inline int neigh_event_send(struct neighbour *neigh, struct sk_buff *skb) +{ + return neigh_event_send_probe(neigh, skb, true); +} + #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) static inline int neigh_hh_bridge(struct hh_cache *hh, struct sk_buff *skb) { --- a/net/core/neighbour.c +++ b/net/core/neighbour.c @@ -1133,7 +1133,8 @@ out: neigh_release(neigh); } -int __neigh_event_send(struct neighbour *neigh, struct sk_buff *skb) +int __neigh_event_send(struct neighbour *neigh, struct sk_buff *skb, + const bool immediate_ok) { int rc; bool immediate_probe = false; @@ -1154,12 +1155,17 @@ int __neigh_event_send(struct neighbour atomic_set(&neigh->probes, NEIGH_VAR(neigh->parms, UCAST_PROBES)); neigh_del_timer(neigh); - neigh->nud_state = NUD_INCOMPLETE; + neigh->nud_state = NUD_INCOMPLETE; neigh->updated = now; - next = now + max(NEIGH_VAR(neigh->parms, RETRANS_TIME), - HZ/100); + if (!immediate_ok) { + next = now + 1; + } else { + immediate_probe = true; + next = now + max(NEIGH_VAR(neigh->parms, + RETRANS_TIME), + HZ / 100); + } neigh_add_timer(neigh, next); - immediate_probe = true; } else { neigh->nud_state = NUD_FAILED; neigh->updated = jiffies; @@ -1571,7 +1577,7 @@ static void neigh_managed_work(struct wo write_lock_bh(&tbl->lock); list_for_each_entry(neigh, &tbl->managed_list, managed_list) - neigh_event_send(neigh, NULL); + neigh_event_send_probe(neigh, NULL, false); queue_delayed_work(system_power_efficient_wq, &tbl->managed_work, NEIGH_VAR(&tbl->parms, DELAY_PROBE_TIME)); write_unlock_bh(&tbl->lock);