Subject: CVE-2021-47024: vsock/virtio: free queued packets when closing socket

From: Greg Kroah-Hartman <[email-masked]>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

vsock/virtio: free queued packets when closing socket

As reported by syzbot [1], there is a memory leak while closing the
socket. We partially solved this issue with commit ac03046ece2b
("vsock/virtio: free packets during the socket release"), but we
forgot to drain the RX queue when the socket is definitely closed by
the scheduled work.

To avoid future issues, let's use the new virtio_transport_remove_sock()
to drain the RX queue before removing the socket from the af_vsock lists
calling vsock_remove_sock().

[1] https://syzkaller.appspot.com/bug?extid=24452624fc4c571eedd9

The Linux kernel CVE team has assigned CVE-2021-47024 to this issue.

Affected and fixed versions
===========================

	Issue introduced in 5.2 with commit ac03046ece2b and fixed in 5.10.37 with commit b605673b523f
	Issue introduced in 5.2 with commit ac03046ece2b and fixed in 5.11.21 with commit 27691665145e
	Issue introduced in 5.2 with commit ac03046ece2b and fixed in 5.12.4 with commit 37c38674ef2f
	Issue introduced in 5.2 with commit ac03046ece2b and fixed in 5.13 with commit 8432b8114957
	Issue introduced in 4.9.179 with commit 4ea082cd3c40
	Issue introduced in 4.14.122 with commit 4e539fa2dec4
	Issue introduced in 4.19.46 with commit 4af8a327aeba
	Issue introduced in 5.0.19 with commit 51adb8ebe8c1
	Issue introduced in 5.1.5 with commit 7d29c9ad0ed5

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2021-47024
will be updated if fixes are backported, please check that for the most
up to date information about this issue.

Affected files
==============

The file(s) affected by this issue are:
	net/vmw_vsock/virtio_transport_common.c

Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/b605673b523fe33abeafb2136759bcbc9c1e6ebf
	https://git.kernel.org/stable/c/27691665145e74a45034a9dccf1150cf1894763a
	https://git.kernel.org/stable/c/37c38674ef2f8d7e8629e5d433c37d6c1273d16b
	https://git.kernel.org/stable/c/8432b8114957235f42e070a16118a7f750de9d39