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* [PATCH AUTOSEL 4.19 01/29] hv_sock: Fix hang when a connection is closed
@ 2019-08-29 10:49 Sasha Levin
  2019-08-29 10:49 ` [PATCH AUTOSEL 4.19 02/29] Revert "dm bufio: fix deadlock with loop device" Sasha Levin
                   ` (27 more replies)
  0 siblings, 28 replies; 33+ messages in thread
From: Sasha Levin @ 2019-08-29 10:49 UTC (permalink / raw)
  To: linux-kernel, stable
  Cc: Dexuan Cui, Sunil Muthuswamy, David S . Miller, Sasha Levin,
	netdev, bcm-kernel-feedback-list

From: Dexuan Cui <decui@microsoft.com>

[ 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 9c7da811d130f..98f193fd5315e 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)
@@ -388,6 +393,9 @@ 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


^ permalink raw reply related	[flat|nested] 33+ messages in thread

end of thread, other threads:[~2019-09-02 15:54 UTC | newest]

Thread overview: 33+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-08-29 10:49 [PATCH AUTOSEL 4.19 01/29] hv_sock: Fix hang when a connection is closed Sasha Levin
2019-08-29 10:49 ` [PATCH AUTOSEL 4.19 02/29] Revert "dm bufio: fix deadlock with loop device" Sasha Levin
2019-08-29 10:49 ` [PATCH AUTOSEL 4.19 03/29] kprobes: Fix potential deadlock in kprobe_optimizer() Sasha Levin
2019-08-29 10:49 ` [PATCH AUTOSEL 4.19 04/29] ALSA: line6: Fix memory leak at line6_init_pcm() error path Sasha Levin
2019-08-29 10:49 ` [PATCH AUTOSEL 4.19 05/29] Blk-iolatency: warn on negative inflight IO counter Sasha Levin
2019-08-29 10:49 ` [PATCH AUTOSEL 4.19 06/29] blk-iolatency: fix STS_AGAIN handling Sasha Levin
2019-08-29 10:49 ` [PATCH AUTOSEL 4.19 07/29] {nl,mac}80211: fix interface combinations on crypto controlled devices Sasha Levin
2019-08-29 10:49 ` [PATCH AUTOSEL 4.19 08/29] timekeeping: Use proper ktime_add when adding nsecs in coarse offset Sasha Levin
2019-08-29 10:49 ` [PATCH AUTOSEL 4.19 09/29] selftests: fib_rule_tests: use pre-defined DEV_ADDR Sasha Levin
2019-08-29 10:49 ` [PATCH AUTOSEL 4.19 10/29] x86/ftrace: Fix warning and considate ftrace_jmp_replace() and ftrace_call_replace() Sasha Levin
2019-08-29 10:49 ` [PATCH AUTOSEL 4.19 11/29] binder: take read mode of mmap_sem in binder_alloc_free_page() Sasha Levin
2019-08-29 15:13   ` Tyler Hicks
2019-08-30  6:29     ` Greg Kroah-Hartman
2019-08-30  7:30       ` Tyler Hicks
2019-09-02 15:54         ` Greg Kroah-Hartman
2019-08-29 10:49 ` [PATCH AUTOSEL 4.19 12/29] powerpc/64: mark start_here_multiplatform as __ref Sasha Levin
2019-08-29 10:49 ` [PATCH AUTOSEL 4.19 13/29] media: stm32-dcmi: fix irq = 0 case Sasha Levin
2019-08-29 10:49 ` [PATCH AUTOSEL 4.19 14/29] HID: input: fix a4tech horizontal wheel custom usage Sasha Levin
2019-08-29 10:49 ` [PATCH AUTOSEL 4.19 15/29] netfilter: nf_tables: use-after-free in failing rule with bound set Sasha Levin
2019-08-29 10:49 ` [PATCH AUTOSEL 4.19 16/29] userfaultfd_release: always remove uffd flags and clear vm_userfaultfd_ctx Sasha Levin
2019-08-29 10:49 ` [PATCH AUTOSEL 4.19 17/29] arm64: dts: rockchip: enable usb-host regulators at boot on rk3328-rock64 Sasha Levin
2019-08-29 10:49 ` [PATCH AUTOSEL 4.19 18/29] mac80211: fix possible sta leak Sasha Levin
2019-08-29 10:49 ` [PATCH AUTOSEL 4.19 19/29] scripts/decode_stacktrace: match basepath using shell prefix operator, not regex Sasha Levin
2019-08-29 10:50 ` [PATCH AUTOSEL 4.19 20/29] KVM: arm/arm64: Only skip MMIO insn once Sasha Levin
2019-08-29 10:50 ` [PATCH AUTOSEL 4.19 21/29] netfilter: ipset: Actually allow destination MAC address for hash:ip,mac sets too Sasha Levin
2019-08-29 10:50 ` [PATCH AUTOSEL 4.19 22/29] netfilter: ipset: Copy the right MAC address in bitmap:ip,mac and hash:ip,mac sets Sasha Levin
2019-08-29 10:50 ` [PATCH AUTOSEL 4.19 23/29] ALSA: usb-audio: Check mixer unit bitmap yet more strictly Sasha Levin
2019-08-29 10:50 ` [PATCH AUTOSEL 4.19 24/29] riscv: remove unused variable in ftrace Sasha Levin
2019-08-29 10:50 ` [PATCH AUTOSEL 4.19 25/29] nvme-fc: use separate work queue to avoid warning Sasha Levin
2019-08-29 10:50 ` [PATCH AUTOSEL 4.19 26/29] clk: s2mps11: Add used attribute to s2mps11_dt_match Sasha Levin
2019-08-29 10:50 ` [PATCH AUTOSEL 4.19 27/29] remoteproc: qcom: q6v5: shore up resource probe handling Sasha Levin
2019-08-29 10:50 ` [PATCH AUTOSEL 4.19 28/29] modules: always page-align module section allocations Sasha Levin
2019-08-29 10:50 ` [PATCH AUTOSEL 4.19 29/29] kernel/module: Fix mem leak in module_add_modinfo_attrs Sasha Levin

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