CVE-2022-49377: blk-mq: don't touch ->tagset in blk_mq_get_sq_hctx

CVE-2022-49377: blk-mq: don't touch ->tagset in blk_mq_get_sq_hctx

[Greg Kroah-Hartman]

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

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

blk-mq: don't touch ->tagset in blk_mq_get_sq_hctx

blk_mq_run_hw_queues() could be run when there isn't queued request and
after queue is cleaned up, at that time tagset is freed, because tagset
lifetime is covered by driver, and often freed after blk_cleanup_queue()
returns.

So don't touch ->tagset for figuring out current default hctx by the mapping
built in request queue, so use-after-free on tagset can be avoided. Meantime
this way should be fast than retrieving mapping from tagset.

The Linux kernel CVE team has assigned CVE-2022-49377 to this issue.


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

	Issue introduced in 5.12 with commit b6e68ee82585f2ee890b0a897a6aacbf49a467bb and fixed in 5.15.47 with commit 460aa288c5cd0544dcf933a2f0ad0e8c6d2d35ff
	Issue introduced in 5.12 with commit b6e68ee82585f2ee890b0a897a6aacbf49a467bb and fixed in 5.17.15 with commit b140bac470b4f707cda59c7266214246238661df
	Issue introduced in 5.12 with commit b6e68ee82585f2ee890b0a897a6aacbf49a467bb and fixed in 5.18.4 with commit 70fdd922c7bf8949f8df109cf2635dff64c90392
	Issue introduced in 5.12 with commit b6e68ee82585f2ee890b0a897a6aacbf49a467bb and fixed in 5.19 with commit 5d05426e2d5fd7df8afc866b78c36b37b00188b7

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-2022-49377
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:
	block/blk-mq.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/460aa288c5cd0544dcf933a2f0ad0e8c6d2d35ff
	https://git.kernel.org/stable/c/b140bac470b4f707cda59c7266214246238661df
	https://git.kernel.org/stable/c/70fdd922c7bf8949f8df109cf2635dff64c90392
	https://git.kernel.org/stable/c/5d05426e2d5fd7df8afc866b78c36b37b00188b7