CVE-2026-68222: media: msi2500: Return queued buffers on start_streaming() failure

CVE-2026-68222: media: msi2500: Return queued buffers on start_streaming() failure

[Greg Kroah-Hartman]

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

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

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

media: msi2500: 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.

msi2500_start_streaming() had five error paths that all hit this trap
and were further tangled by ret-overwriting between calls:

  - -ENODEV when the USB device was already disconnected
  - -ERESTARTSYS when mutex_lock_interruptible() was interrupted
  - msi2500_set_usb_adc() failure: ret was silently overwritten by
    the next call (msi2500_isoc_init), so the error was lost entirely
  - msi2500_isoc_init() failure: cleanup_queued_bufs was called, but
    the function then fell through to msi2500_ctrl_msg() and again
    masked the original error by overwriting ret
  - msi2500_ctrl_msg(CMD_START_STREAMING) failure: no cleanup at all,
    leaving isoc URBs submitted with no way for the driver to consume
    them

Consolidate the error paths into a small goto chain.  Every failure
now stops the function, drains the queued-buffer list, and returns
the real error code.  The ctrl_msg failure path also rolls back the
preceding msi2500_isoc_init() via msi2500_isoc_cleanup() before
unlocking and draining.

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 Linux kernel CVE team has assigned CVE-2026-68222 to this issue.


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

	Issue introduced in 3.12 with commit 977e444f59ad16eedf66acae4f357011c74da291 and fixed in 6.6.148 with commit 1d58229b330b7f67fbfa07e0f2a8a51fbeafaa9a
	Issue introduced in 3.12 with commit 977e444f59ad16eedf66acae4f357011c74da291 and fixed in 6.12.101 with commit bab9d5a67d4db96ae8c187b92b37979911302a10
	Issue introduced in 3.12 with commit 977e444f59ad16eedf66acae4f357011c74da291 and fixed in 6.18.42 with commit 264b5380c4f8aa92dbc2983ecd2b627f1d5e0061
	Issue introduced in 3.12 with commit 977e444f59ad16eedf66acae4f357011c74da291 and fixed in 7.1.6 with commit 3673cb0a5711e910074d69201da9e1535c03f97a
	Issue introduced in 3.12 with commit 977e444f59ad16eedf66acae4f357011c74da291 and fixed in 7.2-rc1 with commit 7201c17786a498497bca57752883b90914d405ac

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-2026-68222
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/usb/msi2500/msi2500.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/1d58229b330b7f67fbfa07e0f2a8a51fbeafaa9a
	https://git.kernel.org/stable/c/bab9d5a67d4db96ae8c187b92b37979911302a10
	https://git.kernel.org/stable/c/264b5380c4f8aa92dbc2983ecd2b627f1d5e0061
	https://git.kernel.org/stable/c/3673cb0a5711e910074d69201da9e1535c03f97a
	https://git.kernel.org/stable/c/7201c17786a498497bca57752883b90914d405ac