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a8ba86c965
There was a race condition between bind() and listen() that was hit very rarely when using Kata Containers and Cloud-Hypervisor. It's been identified the problem is really coming from the virtio-vsock driver, which is fixed by those new kernel patches uploaded for each version of the kernels used by Kata Containers. Fixes #932 Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
50 lines
2.2 KiB
Diff
50 lines
2.2 KiB
Diff
From ac1956caf20f8ac0589f69b2d5fcc81e6ba7c71a Mon Sep 17 00:00:00 2001
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From: Sebastien Boeuf <sebastien.boeuf@intel.com>
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Date: Thu, 13 Feb 2020 08:50:38 +0100
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Subject: [PATCH] net: virtio_vsock: Fix race condition between bind and listen
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Whenever the vsock backend on the host sends a packet through the RX
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queue, it expects an answer on the TX queue. Unfortunately, there is one
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case where the host side will hang waiting for the answer and will
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effectively never recover.
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This issue happens when the guest side starts binding to the socket,
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which insert a new bound socket into the list of already bound sockets.
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At this time, we expect the guest to also start listening, which will
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trigger the sk_state to move from TCP_CLOSE to TCP_LISTEN. The problem
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occurs if the host side queued a RX packet and triggered an interrupt
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right between the end of the binding process and the beginning of the
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listening process. In this specific case, the function processing the
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packet virtio_transport_recv_pkt() will find a bound socket, which means
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it will hit the switch statement checking for the sk_state, but the
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state won't be changed into TCP_LISTEN yet, which leads the code to pick
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the default statement. This default statement will only free the buffer,
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while it should also respond to the host side, by sending a packet on
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its TX queue.
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In order to simply fix this unfortunate chain of events, it is important
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that in case the default statement is entered, and because at this stage
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we know the host side is waiting for an answer, we must send back a
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packet containing the operation VIRTIO_VSOCK_OP_RST.
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Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
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---
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net/vmw_vsock/virtio_transport_common.c | 1 +
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1 file changed, 1 insertion(+)
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diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
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index fb2060dffb0a..696e9a03ad0f 100644
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--- a/net/vmw_vsock/virtio_transport_common.c
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+++ b/net/vmw_vsock/virtio_transport_common.c
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@@ -1127,6 +1127,7 @@ void virtio_transport_recv_pkt(struct virtio_vsock_pkt *pkt)
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virtio_transport_free_pkt(pkt);
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break;
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default:
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+ (void)virtio_transport_reset_no_sock(pkt);
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virtio_transport_free_pkt(pkt);
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break;
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}
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--
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2.20.1
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