CVE-2026-68214: media: rtl2832: fix use-after-free in rtl2832_remove()

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

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

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

media: rtl2832: fix use-after-free in rtl2832_remove()

cancel_delayed_work_sync() is called before i2c_mux_del_adapters()
in rtl2832_remove(). While the cancel waits for any running instance
of i2c_gate_work to finish, it does not prevent the timer from being
rescheduled by a concurrent thread.

During probe, the r820t_attach() call attempts I2C transfers through
the mux adapter. These transfers go through i2c_mux_master_xfer(),
which calls rtl2832_deselect() after the transfer completes,
rescheduling i2c_gate_work via schedule_delayed_work(). If this
transfer is still in flight when rtl2832_remove() runs,
rtl2832_deselect() can reschedule i2c_gate_work after it has been
cancelled, causing a use-after-free when kfree(dev) is called.

Fix this by calling i2c_mux_del_adapters() before
cancel_delayed_work_sync(). Once the mux adapter is unregistered, no
new I2C transfers can go through it, so rtl2832_deselect() can no
longer reschedule i2c_gate_work. The subsequent
cancel_delayed_work_sync() is then guaranteed to be final.

The Linux kernel CVE team has assigned CVE-2026-68214 to this issue.


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

	Issue introduced in 4.7 with commit cddcc40b1b1553010acb89add84c64b5d123ec94 and fixed in 6.6.148 with commit 9acd5bbbe1df8e487e49488692c224496d4c9e16
	Issue introduced in 4.7 with commit cddcc40b1b1553010acb89add84c64b5d123ec94 and fixed in 6.12.101 with commit 24bef237eef8dd1ebcffb129ba21891ddad0d309
	Issue introduced in 4.7 with commit cddcc40b1b1553010acb89add84c64b5d123ec94 and fixed in 6.18.42 with commit 2c71bda6edc630a1f8c3c45d8df5fc22d234e042
	Issue introduced in 4.7 with commit cddcc40b1b1553010acb89add84c64b5d123ec94 and fixed in 7.1.6 with commit 90d781711418881f8c836c2a859cc2886625d750
	Issue introduced in 4.7 with commit cddcc40b1b1553010acb89add84c64b5d123ec94 and fixed in 7.2-rc1 with commit 680daf40a82d483949f87f0d8f98639dc47e610c

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-2026-68214
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-frontends/rtl2832.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/9acd5bbbe1df8e487e49488692c224496d4c9e16
	https://git.kernel.org/stable/c/24bef237eef8dd1ebcffb129ba21891ddad0d309
	https://git.kernel.org/stable/c/2c71bda6edc630a1f8c3c45d8df5fc22d234e042
	https://git.kernel.org/stable/c/90d781711418881f8c836c2a859cc2886625d750
	https://git.kernel.org/stable/c/680daf40a82d483949f87f0d8f98639dc47e610c