CVE-2021-47039: ataflop: potential out of bounds in do_format()

CVE-2021-47039: ataflop: potential out of bounds in do_format()

[Greg Kroah-Hartman]

From: gregkh@kernel.org

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

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

ataflop: potential out of bounds in do_format()

The function uses "type" as an array index:

	q = unit[drive].disk[type]->queue;

Unfortunately the bounds check on "type" isn't done until later in the
function.  Fix this by moving the bounds check to the start.

The Linux kernel CVE team has assigned CVE-2021-47039 to this issue.


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

	Issue introduced in 5.11 with commit bf9c0538e485 and fixed in 5.11.21 with commit 07f86aa8f4fe
	Issue introduced in 5.11 with commit bf9c0538e485 and fixed in 5.12.4 with commit 2a3a8bbca28b
	Issue introduced in 5.11 with commit bf9c0538e485 and fixed in 5.13 with commit 1ffec389a643

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-2021-47039
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/block/ataflop.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/07f86aa8f4fe077be1b018cc177eb8c6573e5671
	https://git.kernel.org/stable/c/2a3a8bbca28b899806844c00d49ed1b7ccb50957
	https://git.kernel.org/stable/c/1ffec389a6431782a8a28805830b6fae9bf00af1