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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org, Dexuan Cui <decui@microsoft.com>,
	Sunil Muthuswamy <sunilmut@microsoft.com>,
	"David S. Miller" <davem@davemloft.net>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.14 14/21] hv_sock: Fix hang when a connection is closed
Date: Fri, 13 Sep 2019 14:07:07 +0100	[thread overview]
Message-ID: <20190913130507.116698849@linuxfoundation.org> (raw)
In-Reply-To: <20190913130501.285837292@linuxfoundation.org>

[ Upstream commit 685703b497bacea8765bb409d6b73455b73c540e ]

There is a race condition for an established connection that is being closed
by the guest: the refcnt is 4 at the end of hvs_release() (Note: here the
'remove_sock' is false):

1 for the initial value;
1 for the sk being in the bound list;
1 for the sk being in the connected list;
1 for the delayed close_work.

After hvs_release() finishes, __vsock_release() -> sock_put(sk) *may*
decrease the refcnt to 3.

Concurrently, hvs_close_connection() runs in another thread:
  calls vsock_remove_sock() to decrease the refcnt by 2;
  call sock_put() to decrease the refcnt to 0, and free the sk;
  next, the "release_sock(sk)" may hang due to use-after-free.

In the above, after hvs_release() finishes, if hvs_close_connection() runs
faster than "__vsock_release() -> sock_put(sk)", then there is not any issue,
because at the beginning of hvs_close_connection(), the refcnt is still 4.

The issue can be resolved if an extra reference is taken when the
connection is established.

Fixes: a9eeb998c28d ("hv_sock: Add support for delayed close")
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Reviewed-by: Sunil Muthuswamy <sunilmut@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/vmw_vsock/hyperv_transport.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/net/vmw_vsock/hyperv_transport.c b/net/vmw_vsock/hyperv_transport.c
index 52ac3e49c7efd..ec72a5edaa1b8 100644
--- a/net/vmw_vsock/hyperv_transport.c
+++ b/net/vmw_vsock/hyperv_transport.c
@@ -320,6 +320,11 @@ static void hvs_close_connection(struct vmbus_channel *chan)
 	lock_sock(sk);
 	hvs_do_close_lock_held(vsock_sk(sk), true);
 	release_sock(sk);
+
+	/* Release the refcnt for the channel that's opened in
+	 * hvs_open_connection().
+	 */
+	sock_put(sk);
 }
 
 static void hvs_open_connection(struct vmbus_channel *chan)
@@ -389,6 +394,9 @@ static void hvs_open_connection(struct vmbus_channel *chan)
 	}
 
 	set_per_channel_state(chan, conn_from_host ? new : sk);
+
+	/* This reference will be dropped by hvs_close_connection(). */
+	sock_hold(conn_from_host ? new : sk);
 	vmbus_set_chn_rescind_callback(chan, hvs_close_connection);
 
 	/* Set the pending send size to max packet size to always get
-- 
2.20.1




  parent reply	other threads:[~2019-09-13 13:33 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-13 13:06 [PATCH 4.14 00/21] 4.14.144-stable review Greg Kroah-Hartman
2019-09-13 13:06 ` [PATCH 4.14 01/21] ALSA: hda - Fix potential endless loop at applying quirks Greg Kroah-Hartman
2019-09-13 13:06 ` [PATCH 4.14 02/21] ALSA: hda/realtek - Fix overridden device-specific initialization Greg Kroah-Hartman
2019-09-13 13:06 ` [PATCH 4.14 03/21] ALSA: hda/realtek - Fix the problem of two front mics on a ThinkCentre Greg Kroah-Hartman
2019-09-13 13:06 ` [PATCH 4.14 04/21] sched/fair: Dont assign runtime for throttled cfs_rq Greg Kroah-Hartman
2019-09-13 13:06 ` [PATCH 4.14 05/21] drm/vmwgfx: Fix double free in vmw_recv_msg() Greg Kroah-Hartman
2019-09-13 13:06 ` [PATCH 4.14 06/21] powerpc/tm: Fix FP/VMX unavailable exceptions inside a transaction Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 4.14 07/21] xfrm: clean up xfrm protocol checks Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 4.14 08/21] ip6: fix skb leak in ip6frag_expire_frag_queue() Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 4.14 09/21] PCI: designware-ep: Fix find_first_zero_bit() usage Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 4.14 10/21] PCI: dra7xx: Fix legacy INTD IRQ handling Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 4.14 11/21] vhost/test: fix build for vhost test Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 4.14 12/21] batman-adv: fix uninit-value in batadv_netlink_get_ifindex() Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 4.14 13/21] batman-adv: Only read OGM tvlv_len after buffer len check Greg Kroah-Hartman
2019-09-13 13:07 ` Greg Kroah-Hartman [this message]
2019-09-13 13:07 ` [PATCH 4.14 15/21] powerpc/64: mark start_here_multiplatform as __ref Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 4.14 16/21] arm64: dts: rockchip: enable usb-host regulators at boot on rk3328-rock64 Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 4.14 17/21] scripts/decode_stacktrace: match basepath using shell prefix operator, not regex Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 4.14 18/21] clk: s2mps11: Add used attribute to s2mps11_dt_match Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 4.14 19/21] kernel/module: Fix mem leak in module_add_modinfo_attrs Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 4.14 20/21] vhost: block speculation of translated descriptors Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 4.14 21/21] vhost: make sure log_num < in_num Greg Kroah-Hartman
2019-09-13 19:59 ` [PATCH 4.14 00/21] 4.14.144-stable review kernelci.org bot
2019-09-14  4:03 ` Naresh Kamboju
2019-09-14 14:06 ` Guenter Roeck
2019-09-15 13:35 ` Greg Kroah-Hartman
2019-09-16 10:55 ` Jon Hunter

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