CVE-2026-68213: media: rtl2832_sdr: Return queued buffers on start_streaming() failure

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

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

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

media: rtl2832_sdr: Return queued buffers on start_streaming() failure

The vb2 framework hands buffers to the driver via buf_queue() before
calling start_streaming().  If start_streaming() returns an error
without first returning those buffers via vb2_buffer_done(),
vb2_start_streaming() fires WARN_ON(owned_by_drv_count) and the queued
buffers leak.

rtl2832_sdr_start_streaming() had multiple error paths that hit this
trap: two direct early returns (-ENODEV, -ERESTARTSYS), plus six
`goto err` paths covering subdev s_power, tuner setup, ADC setup,
stream-buffer allocation, urb allocation, and urb submission failures.
None of them returned the queued buffers.

The original function had no distinct success exit and fell straight
through into the err label, which previously only did mutex_unlock and
"return ret".  Adding queued-buffer cleanup at err must therefore be
paired with an explicit success return; otherwise every successful
start would also drain the buffer queue and kill streaming.  Add that
success return, then add rtl2832_sdr_cleanup_queued_bufs() at the err
label and before each early return.

The cleanup helper takes a vb2_buffer_state argument so that the
start_streaming error paths can pass VB2_BUF_STATE_QUEUED (as
expected by userspace on start_streaming failure) while stop_streaming
keeps its existing VB2_BUF_STATE_ERROR semantics.

This mirrors the uvcvideo fix in commit 4cf3b6fd54eb ("media: uvcvideo:
Return queued buffers on start_streaming() failure").

The err label still does not roll back power_ctrl(), frontend_ctrl(),
the POWER_ON flag, or stream/URB allocations that may have happened
before the failing step.  Those are pre-existing leaks of a different
class and are not addressed here.

The Linux kernel CVE team has assigned CVE-2026-68213 to this issue.


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

	Issue introduced in 3.15 with commit 771138920eafa399f68d3492c8a75dfeea23474b and fixed in 6.6.148 with commit 465dc8e71d2db2ed603e749fa71392bcdccf07eb
	Issue introduced in 3.15 with commit 771138920eafa399f68d3492c8a75dfeea23474b and fixed in 6.12.101 with commit 0b08c0403cf672a121ace4eff647a9b240bd4e1b
	Issue introduced in 3.15 with commit 771138920eafa399f68d3492c8a75dfeea23474b and fixed in 6.18.42 with commit 894e83509c66910112b9eaeaa8cd66cd9806db91
	Issue introduced in 3.15 with commit 771138920eafa399f68d3492c8a75dfeea23474b and fixed in 7.1.6 with commit fc0b18782aab4e35078efe72863df8eab46560a8
	Issue introduced in 3.15 with commit 771138920eafa399f68d3492c8a75dfeea23474b and fixed in 7.2-rc1 with commit 33ca0aab6f4bd90921fc1395478f38f72c4d19af

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-2026-68213
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_sdr.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/465dc8e71d2db2ed603e749fa71392bcdccf07eb
	https://git.kernel.org/stable/c/0b08c0403cf672a121ace4eff647a9b240bd4e1b
	https://git.kernel.org/stable/c/894e83509c66910112b9eaeaa8cd66cd9806db91
	https://git.kernel.org/stable/c/fc0b18782aab4e35078efe72863df8eab46560a8
	https://git.kernel.org/stable/c/33ca0aab6f4bd90921fc1395478f38f72c4d19af