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FreeBSD-SA-22:10.aio                                        Security Advisory
                                                          The FreeBSD Project

Topic:          AIO credential reference count leak

Category:       core
Module:         kernel
Announced:      2022-08-09
Credits:	Chris J-D <chris@accessvector.net>
Affects:        FreeBSD 12.3, FreeBSD 13.0
Corrected:      2021-10-01 00:32:22 UTC (stable/13, 13.0-STABLE)
                2022-08-09 20:00:24 UTC (releng/13.0, 13.0-RELEASE-p12)
                2022-06-27 17:27:50 UTC (stable/12, 12.3-STABLE)
                2022-08-09 19:59:44 UTC (releng/12.3, 12.3-RELEASE-p6)
CVE Name:       CVE-2022-23090

For general information regarding FreeBSD Security Advisories,
including descriptions of the fields above, security branches, and the
following sections, please visit <URL:https://security.FreeBSD.org/>.

I.   Background

FreeBSD's aio(4) subsystem implements asynchronous I/O.

II.  Problem Description

The aio_aqueue function, used by the lio_listio system call, fails to release
a reference to a credential in an error case.

III. Impact

An attacker may cause the reference count to overflow, leading to a
use after free (UAF).

IV.  Workaround

No workaround is available.

V.   Solution

Upgrade your vulnerable system to a supported FreeBSD stable or
release / security branch (releng) dated after the correction date,
and reboot.

Perform one of the following:

1) To update your vulnerable system via a binary patch:

Systems running a RELEASE version of FreeBSD on the amd64, i386, or
(on FreeBSD 13 and later) arm64 platforms can be updated via the
freebsd-update(8) utility:

# freebsd-update fetch
# freebsd-update install
# shutdown -r +10min "Rebooting for a security update"

2) To update your vulnerable system via a source code patch:

The following patches have been verified to apply to the applicable
FreeBSD release branches.

a) Download the relevant patch from the location below, and verify the
detached PGP signature using your PGP utility.

[FreeBSD 12.3]
# fetch https://security.FreeBSD.org/patches/SA-22:10/aio.12.patch
# fetch https://security.FreeBSD.org/patches/SA-22:10/aio.12.patch.asc
# gpg --verify aio.12.patch.asc

[FreeBSD 13.0]
# fetch https://security.FreeBSD.org/patches/SA-22:10/aio.13.patch
# fetch https://security.FreeBSD.org/patches/SA-22:10/aio.13.patch.asc
# gpg --verify aio.13.patch.asc

b) Apply the patch.  Execute the following commands as root:

# cd /usr/src
# patch < /path/to/patch

c) Recompile your kernel as described in
<URL:https://www.FreeBSD.org/handbook/kernelconfig.html> and reboot the
system.

VI.  Correction details

This issue is corrected by the corresponding Git commit hash or Subversion
revision number in the following stable and release branches:

Branch/path                             Hash                     Revision
- -------------------------------------------------------------------------
stable/13/                              9499d3c1e40d    stable/13-n247480
releng/13.0/                            c864c8cf08a9  releng/13.0-n244801
stable/12/                                                        r372172
releng/12.3/                                                      r372379
- -------------------------------------------------------------------------

For FreeBSD 13 and later:

Run the following command to see which files were modified by a
particular commit:

# git show --stat <commit hash>

Or visit the following URL, replacing NNNNNN with the hash:

<URL:https://cgit.freebsd.org/src/commit/?id=NNNNNN>

To determine the commit count in a working tree (for comparison against
nNNNNNN in the table above), run:

# git rev-list --count --first-parent HEAD

For FreeBSD 12 and earlier:

Run the following command to see which files were modified by a particular
revision, replacing NNNNNN with the revision number:

# svn diff -cNNNNNN --summarize svn://svn.freebsd.org/base

Or visit the following URL, replacing NNNNNN with the revision number:

<URL:https://svnweb.freebsd.org/base?view=revision&revision=NNNNNN>

VII. References

<URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2022-23090>

<URL:https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=258698>

The latest revision of this advisory is available at
<URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-22:10.aio.asc>
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