Subject: CVE-2022-48890: scsi: storvsc: Fix swiotlb bounce buffer leak in confidential VM

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

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

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

scsi: storvsc: Fix swiotlb bounce buffer leak in confidential VM

storvsc_queuecommand() maps the scatter/gather list using scsi_dma_map(),
which in a confidential VM allocates swiotlb bounce buffers. If the I/O
submission fails in storvsc_do_io(), the I/O is typically retried by higher
level code, but the bounce buffer memory is never freed.  The mostly like
cause of I/O submission failure is a full VMBus channel ring buffer, which
is not uncommon under high I/O loads.  Eventually enough bounce buffer
memory leaks that the confidential VM can't do any I/O. The same problem
can arise in a non-confidential VM with kernel boot parameter
swiotlb=force.

Fix this by doing scsi_dma_unmap() in the case of an I/O submission
error, which frees the bounce buffer memory.

The Linux kernel CVE team has assigned CVE-2022-48890 to this issue.

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

	Issue introduced in 5.17 with commit 743b237c3a7b and fixed in 6.1.7 with commit 87c71e88f6a6
	Issue introduced in 5.17 with commit 743b237c3a7b and fixed in 6.2 with commit 67ff3d0a49f3

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-2022-48890
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/scsi/storvsc_drv.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/87c71e88f6a6619ffb1ff88f84dff48ef6d57adb
	https://git.kernel.org/stable/c/67ff3d0a49f3d445c3922e30a54e03c161da561e