CVE-2022-49191: mxser: fix xmit_buf leak in activate when LSR == 0xff

CVE-2022-49191: mxser: fix xmit_buf leak in activate when LSR == 0xff

[Greg Kroah-Hartman]

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

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

mxser: fix xmit_buf leak in activate when LSR == 0xff

When LSR is 0xff in ->activate() (rather unlike), we return an error.
Provided ->shutdown() is not called when ->activate() fails, nothing
actually frees the buffer in this case.

Fix this by properly freeing the buffer in a designated label. We jump
there also from the "!info->type" if now too.

The Linux kernel CVE team has assigned CVE-2022-49191 to this issue.


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

	Issue introduced in 2.6.33 with commit 6769140d304731f0a3b177470a2adb4bacd9036b and fixed in 4.9.311 with commit 376922045009f8ea2d20a8fa3475e95b47c41690
	Issue introduced in 2.6.33 with commit 6769140d304731f0a3b177470a2adb4bacd9036b and fixed in 4.14.276 with commit 125b7c929fc9b1e5eaa344bceb6367dfa6fd3f9d
	Issue introduced in 2.6.33 with commit 6769140d304731f0a3b177470a2adb4bacd9036b and fixed in 4.19.238 with commit 685b6d16bf89595310b5d61394c9b97cc9505c7c
	Issue introduced in 2.6.33 with commit 6769140d304731f0a3b177470a2adb4bacd9036b and fixed in 5.4.189 with commit 996291d06851a26678a0fab488b6e1f0677c0576
	Issue introduced in 2.6.33 with commit 6769140d304731f0a3b177470a2adb4bacd9036b and fixed in 5.10.110 with commit 2cd05c38a27bee7fb42aa4d43174d68ac55dac0f
	Issue introduced in 2.6.33 with commit 6769140d304731f0a3b177470a2adb4bacd9036b and fixed in 5.15.33 with commit b125b08dbee3611f03f53b71471813ed4ccafcdd
	Issue introduced in 2.6.33 with commit 6769140d304731f0a3b177470a2adb4bacd9036b and fixed in 5.16.19 with commit 6c9041b2f90c0eace73106f22350e1d2c98f5edc
	Issue introduced in 2.6.33 with commit 6769140d304731f0a3b177470a2adb4bacd9036b and fixed in 5.17.2 with commit 6dffc2035fbaada60ca8db59e0962e34f760370a
	Issue introduced in 2.6.33 with commit 6769140d304731f0a3b177470a2adb4bacd9036b and fixed in 5.18 with commit cd3a4907ee334b40d7aa880c7ab310b154fd5cd4

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-2022-49191
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/tty/mxser.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/376922045009f8ea2d20a8fa3475e95b47c41690
	https://git.kernel.org/stable/c/125b7c929fc9b1e5eaa344bceb6367dfa6fd3f9d
	https://git.kernel.org/stable/c/685b6d16bf89595310b5d61394c9b97cc9505c7c
	https://git.kernel.org/stable/c/996291d06851a26678a0fab488b6e1f0677c0576
	https://git.kernel.org/stable/c/2cd05c38a27bee7fb42aa4d43174d68ac55dac0f
	https://git.kernel.org/stable/c/b125b08dbee3611f03f53b71471813ed4ccafcdd
	https://git.kernel.org/stable/c/6c9041b2f90c0eace73106f22350e1d2c98f5edc
	https://git.kernel.org/stable/c/6dffc2035fbaada60ca8db59e0962e34f760370a
	https://git.kernel.org/stable/c/cd3a4907ee334b40d7aa880c7ab310b154fd5cd4