CVE-2021-47071: uio_hv_generic: Fix a memory leak in error handling paths

CVE-2021-47071: uio_hv_generic: Fix a memory leak in error handling paths

[Greg Kroah-Hartman]

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

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

uio_hv_generic: Fix a memory leak in error handling paths

If 'vmbus_establish_gpadl()' fails, the (recv|send)_gpadl will not be
updated and 'hv_uio_cleanup()' in the error handling path will not be
able to free the corresponding buffer.

In such a case, we need to free the buffer explicitly.

The Linux kernel CVE team has assigned CVE-2021-47071 to this issue.


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

	Issue introduced in 4.20 with commit cdfa835c6e5e and fixed in 5.4.122 with commit cdd91637d4ef
	Issue introduced in 4.20 with commit cdfa835c6e5e and fixed in 5.10.40 with commit d84b5e912212
	Issue introduced in 4.20 with commit cdfa835c6e5e and fixed in 5.12.7 with commit 53486c467e35
	Issue introduced in 4.20 with commit cdfa835c6e5e and fixed in 5.13 with commit 3ee098f96b8b

Please see https://www.kernel.org or 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-2021-47071
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:
	drivers/uio/uio_hv_generic.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/cdd91637d4ef33e2be19a8e16e72e7d00c996d76
	https://git.kernel.org/stable/c/d84b5e912212b05f6b5bde9f682046accfbe0354
	https://git.kernel.org/stable/c/53486c467e356e06aa37047c984fccd64d78c827
	https://git.kernel.org/stable/c/3ee098f96b8b6c1a98f7f97915f8873164e6af9d