Subject: CVE-2024-27043: media: edia: dvbdev: fix a use-after-free

From: Greg Kroah-Hartman <[email-masked]>

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

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

media: edia: dvbdev: fix a use-after-free

In dvb_register_device, *pdvbdev is set equal to dvbdev, which is freed
in several error-handling paths. However, *pdvbdev is not set to NULL
after dvbdev's deallocation, causing use-after-frees in many places,
for example, in the following call chain:

budget_register
  |-> dvb_dmxdev_init
        |-> dvb_register_device
  |-> dvb_dmxdev_release
        |-> dvb_unregister_device
              |-> dvb_remove_device
                    |-> dvb_device_put
                          |-> kref_put

When calling dvb_unregister_device, dmxdev->dvbdev (i.e. *pdvbdev in
dvb_register_device) could point to memory that had been freed in
dvb_register_device. Thereafter, this pointer is transferred to
kref_put and triggering a use-after-free.

The Linux kernel CVE team has assigned CVE-2024-27043 to this issue.

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

	Issue introduced in 2.6.21 with commit b61901024776 and fixed in 4.19.311 with commit d0f5c2833382
	Issue introduced in 2.6.21 with commit b61901024776 and fixed in 5.4.273 with commit f20c3270f3ed
	Issue introduced in 2.6.21 with commit b61901024776 and fixed in 5.10.214 with commit 096237039d00
	Issue introduced in 2.6.21 with commit b61901024776 and fixed in 5.15.153 with commit 0d3fe80b6d17
	Issue introduced in 2.6.21 with commit b61901024776 and fixed in 6.1.83 with commit 437a111f79a2
	Issue introduced in 2.6.21 with commit b61901024776 and fixed in 6.6.23 with commit 779e8db7efb2
	Issue introduced in 2.6.21 with commit b61901024776 and fixed in 6.7.11 with commit 35674111a043
	Issue introduced in 2.6.21 with commit b61901024776 and fixed in 6.8.2 with commit b7586e902128
	Issue introduced in 2.6.21 with commit b61901024776 and fixed in 6.9 with commit 8c64f4cdf4e6

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-2024-27043
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/media/dvb-core/dvbdev.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/d0f5c28333822f9baa5280d813124920720fd856
	https://git.kernel.org/stable/c/f20c3270f3ed5aa6919a87e4de9bf6c05fb57086
	https://git.kernel.org/stable/c/096237039d00c839f3e3a5fe6d001bf0db45b644
	https://git.kernel.org/stable/c/0d3fe80b6d175c220b3e252efc6c6777e700e98e
	https://git.kernel.org/stable/c/437a111f79a2f5b2a5f21e27fdec6f40c8768712
	https://git.kernel.org/stable/c/779e8db7efb22316c8581d6c229636d2f5694a62
	https://git.kernel.org/stable/c/35674111a043b0482a9bc69da8850a83f465b07d
	https://git.kernel.org/stable/c/b7586e902128e4fb7bfbb661cb52e4215a65637b
	https://git.kernel.org/stable/c/8c64f4cdf4e6cc5682c52523713af8c39c94e6d5