CVE-2026-72458: apparmor: fix NULL pointer dereference in unpack_pdb

CVE-2026-72458: apparmor: fix NULL pointer dereference in unpack_pdb

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

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

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

apparmor: fix NULL pointer dereference in unpack_pdb

pdb->dfa could be NULL if unpack_dfa fails, causing a NULL pointer
dereference.

The Linux kernel CVE team has assigned CVE-2026-72458 to this issue.


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

	Issue introduced in 6.17 with commit 2e12c5f060176ede209673e4f63ea5d0e3c5814c and fixed in 6.18.40 with commit fbfdb5a94a48797bea232791e24c38f3aa3063c8
	Issue introduced in 6.17 with commit 2e12c5f060176ede209673e4f63ea5d0e3c5814c and fixed in 7.1.5 with commit 73d86ca950b80cd39ca948e2c518d135bf2308c8
	Issue introduced in 6.17 with commit 2e12c5f060176ede209673e4f63ea5d0e3c5814c and fixed in 7.2-rc1 with commit 7681ca43d2b1c776e62fe77e3167835fb1ab8319

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-2026-72458
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:
	security/apparmor/policy_unpack.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/fbfdb5a94a48797bea232791e24c38f3aa3063c8
	https://git.kernel.org/stable/c/73d86ca950b80cd39ca948e2c518d135bf2308c8
	https://git.kernel.org/stable/c/7681ca43d2b1c776e62fe77e3167835fb1ab8319