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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: David Howells <dhowells@redhat.com>,
	syzbot+72af434e4b3417318f84@syzkaller.appspotmail.com,
	Marc Dionne <marc.dionne@auristor.com>,
	Jeffrey Altman <jaltman@auristor.com>,
	Sasha Levin <sashal@kernel.org>,
	linux-afs@lists.infradead.org, netdev@vger.kernel.org
Subject: [PATCH AUTOSEL 4.19 29/68] rxrpc: Fix potential deadlock
Date: Tue, 13 Aug 2019 22:15:07 -0400
Message-ID: <20190814021548.16001-29-sashal@kernel.org> (raw)
In-Reply-To: <20190814021548.16001-1-sashal@kernel.org>

From: David Howells <dhowells@redhat.com>

[ Upstream commit 60034d3d146b11922ab1db613bce062dddc0327a ]

There is a potential deadlock in rxrpc_peer_keepalive_dispatch() whereby
rxrpc_put_peer() is called with the peer_hash_lock held, but if it reduces
the peer's refcount to 0, rxrpc_put_peer() calls __rxrpc_put_peer() - which
the tries to take the already held lock.

Fix this by providing a version of rxrpc_put_peer() that can be called in
situations where the lock is already held.

The bug may produce the following lockdep report:

============================================
WARNING: possible recursive locking detected
5.2.0-next-20190718 #41 Not tainted
--------------------------------------------
kworker/0:3/21678 is trying to acquire lock:
00000000aa5eecdf (&(&rxnet->peer_hash_lock)->rlock){+.-.}, at: spin_lock_bh
/./include/linux/spinlock.h:343 [inline]
00000000aa5eecdf (&(&rxnet->peer_hash_lock)->rlock){+.-.}, at:
__rxrpc_put_peer /net/rxrpc/peer_object.c:415 [inline]
00000000aa5eecdf (&(&rxnet->peer_hash_lock)->rlock){+.-.}, at:
rxrpc_put_peer+0x2d3/0x6a0 /net/rxrpc/peer_object.c:435

but task is already holding lock:
00000000aa5eecdf (&(&rxnet->peer_hash_lock)->rlock){+.-.}, at: spin_lock_bh
/./include/linux/spinlock.h:343 [inline]
00000000aa5eecdf (&(&rxnet->peer_hash_lock)->rlock){+.-.}, at:
rxrpc_peer_keepalive_dispatch /net/rxrpc/peer_event.c:378 [inline]
00000000aa5eecdf (&(&rxnet->peer_hash_lock)->rlock){+.-.}, at:
rxrpc_peer_keepalive_worker+0x6b3/0xd02 /net/rxrpc/peer_event.c:430

Fixes: 330bdcfadcee ("rxrpc: Fix the keepalive generator [ver #2]")
Reported-by: syzbot+72af434e4b3417318f84@syzkaller.appspotmail.com
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Marc Dionne <marc.dionne@auristor.com>
Reviewed-by: Jeffrey Altman <jaltman@auristor.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/rxrpc/ar-internal.h |  1 +
 net/rxrpc/peer_event.c  |  2 +-
 net/rxrpc/peer_object.c | 18 ++++++++++++++++++
 3 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index 03e0fc8c183f0..a4c341828b72f 100644
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -1057,6 +1057,7 @@ void rxrpc_destroy_all_peers(struct rxrpc_net *);
 struct rxrpc_peer *rxrpc_get_peer(struct rxrpc_peer *);
 struct rxrpc_peer *rxrpc_get_peer_maybe(struct rxrpc_peer *);
 void rxrpc_put_peer(struct rxrpc_peer *);
+void rxrpc_put_peer_locked(struct rxrpc_peer *);
 
 /*
  * proc.c
diff --git a/net/rxrpc/peer_event.c b/net/rxrpc/peer_event.c
index bd2fa3b7caa7e..dc7fdaf20445b 100644
--- a/net/rxrpc/peer_event.c
+++ b/net/rxrpc/peer_event.c
@@ -375,7 +375,7 @@ static void rxrpc_peer_keepalive_dispatch(struct rxrpc_net *rxnet,
 		spin_lock_bh(&rxnet->peer_hash_lock);
 		list_add_tail(&peer->keepalive_link,
 			      &rxnet->peer_keepalive[slot & mask]);
-		rxrpc_put_peer(peer);
+		rxrpc_put_peer_locked(peer);
 	}
 
 	spin_unlock_bh(&rxnet->peer_hash_lock);
diff --git a/net/rxrpc/peer_object.c b/net/rxrpc/peer_object.c
index 5691b7d266ca0..71547e8673b99 100644
--- a/net/rxrpc/peer_object.c
+++ b/net/rxrpc/peer_object.c
@@ -440,6 +440,24 @@ void rxrpc_put_peer(struct rxrpc_peer *peer)
 	}
 }
 
+/*
+ * Drop a ref on a peer record where the caller already holds the
+ * peer_hash_lock.
+ */
+void rxrpc_put_peer_locked(struct rxrpc_peer *peer)
+{
+	const void *here = __builtin_return_address(0);
+	int n;
+
+	n = atomic_dec_return(&peer->usage);
+	trace_rxrpc_peer(peer, rxrpc_peer_put, n, here);
+	if (n == 0) {
+		hash_del_rcu(&peer->hash_link);
+		list_del_init(&peer->keepalive_link);
+		kfree_rcu(peer, rcu);
+	}
+}
+
 /*
  * Make sure all peer records have been discarded.
  */
-- 
2.20.1


  parent reply index

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20190814021548.16001-1-sashal@kernel.org>
2019-08-14  2:14 ` [PATCH AUTOSEL 4.19 06/68] netfilter: ebtables: fix a memory leak bug in compat Sasha Levin
2019-08-14  2:14 ` [PATCH AUTOSEL 4.19 08/68] selftests/bpf: fix sendmsg6_prog on s390 Sasha Levin
2019-08-14  2:14 ` [PATCH AUTOSEL 4.19 09/68] bonding: Force slave speed check after link state recovery for 802.3ad Sasha Levin
2019-08-14  2:14 ` [PATCH AUTOSEL 4.19 10/68] net: mvpp2: Don't check for 3 consecutive Idle frames for 10G links Sasha Levin
2019-08-14  2:14 ` [PATCH AUTOSEL 4.19 11/68] selftests: forwarding: gre_multipath: Enable IPv4 forwarding Sasha Levin
2019-08-14  2:14 ` [PATCH AUTOSEL 4.19 12/68] selftests: forwarding: gre_multipath: Fix flower filters Sasha Levin
2019-08-14  2:14 ` [PATCH AUTOSEL 4.19 13/68] can: dev: call netif_carrier_off() in register_candev() Sasha Levin
2019-08-14  2:14 ` [PATCH AUTOSEL 4.19 14/68] can: mcp251x: add error check when wq alloc failed Sasha Levin
2019-08-14  2:14 ` [PATCH AUTOSEL 4.19 15/68] can: gw: Fix error path of cgw_module_init Sasha Levin
2019-08-14  2:14 ` [PATCH AUTOSEL 4.19 17/68] st21nfca_connectivity_event_received: null check the allocation Sasha Levin
2019-08-14  2:14 ` [PATCH AUTOSEL 4.19 18/68] st_nci_hci_connectivity_event_received: " Sasha Levin
2019-08-14  2:14 ` [PATCH AUTOSEL 4.19 21/68] net: usb: qmi_wwan: Add the BroadMobi BM818 card Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 22/68] qed: RDMA - Fix the hw_ver returned in device attributes Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 23/68] isdn: mISDN: hfcsusb: Fix possible null-pointer dereferences in start_isoc_chain() Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 24/68] mac80211_hwsim: Fix possible null-pointer dereferences in hwsim_dump_radio_nl() Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 25/68] netfilter: ipset: Actually allow destination MAC address for hash:ip,mac sets too Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 26/68] netfilter: ipset: Copy the right MAC address in bitmap:ip,mac and hash:ip,mac sets Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 27/68] netfilter: ipset: Fix rename concurrency with listing Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 28/68] netfilter: ebtables: also count base chain policies Sasha Levin
2019-08-14  2:15 ` Sasha Levin [this message]
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 30/68] rxrpc: Fix the lack of notification when sendmsg() fails on a DATA packet Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 32/68] isdn: hfcsusb: Fix mISDN driver crash caused by transfer buffer on the stack Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 33/68] net: phy: phy_led_triggers: Fix a possible null-pointer dereference in phy_led_trigger_change_speed() Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 36/68] net: usb: pegasus: fix improper read if get_registers() fail Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 37/68] can: sja1000: force the string buffer NULL-terminated Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 38/68] can: peak_usb: " Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 39/68] net/ethernet/qlogic/qed: " Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 52/68] net: cxgb3_main: Fix a resource leak in a error path in 'init_one()' Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 53/68] net: stmmac: Fix issues when number of Queues >= 4 Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 54/68] net: stmmac: tc: Do not return a fragment entry Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 55/68] net: hisilicon: make hip04_tx_reclaim non-reentrant Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 56/68] net: hisilicon: fix hip04-xmit never return TX_BUSY Sasha Levin
2019-08-14  2:15 ` [PATCH AUTOSEL 4.19 57/68] net: hisilicon: Fix dma_map_single failed on arm64 Sasha Levin

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