CVE-2026-68211: media: stm32-dcmipp: 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: stm32-dcmipp: 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.

dcmipp_bytecap_start_streaming() returned -EINVAL when the source
subdevice could not be resolved from the media graph, before
pm_runtime_resume_and_get() and media_pipeline_start() had been called.
The remaining error paths already converge on the err_buffer_done
label, which calls dcmipp_bytecap_all_buffers_done(...,
VB2_BUF_STATE_QUEUED).  Jump to that label directly: the intermediate
err_pm_put / err_media_pipeline_stop labels are skipped, which is
correct because nothing they would undo has happened yet.

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

The Linux kernel CVE team has assigned CVE-2026-68211 to this issue.


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

	Issue introduced in 6.8 with commit 28e0f37722965fa150af31d82101c95fd21aef60 and fixed in 6.18.42 with commit ed342a86bb2f9c1b44a0fc4f6b08c14073946e4f
	Issue introduced in 6.8 with commit 28e0f37722965fa150af31d82101c95fd21aef60 and fixed in 7.1.6 with commit 624af2d4b5e9d3dd366538e4fb4a2a037792a7e3
	Issue introduced in 6.8 with commit 28e0f37722965fa150af31d82101c95fd21aef60 and fixed in 7.2-rc1 with commit ffc8eec06378a340d708c889184ab3e14b57d540

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-2026-68211
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/platform/st/stm32/stm32-dcmipp/dcmipp-bytecap.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/ed342a86bb2f9c1b44a0fc4f6b08c14073946e4f
	https://git.kernel.org/stable/c/624af2d4b5e9d3dd366538e4fb4a2a037792a7e3
	https://git.kernel.org/stable/c/ffc8eec06378a340d708c889184ab3e14b57d540