CVE-2026-89894

Status: UPDATED  |  Advisory ID: CVE-2026-89894

Key Details

Affected Products, Subsystems & Sectors

What to Know

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

media: cx231xx: reject geometry changes while the VBI queue is busy

vidioc_s_fmt_vid_cap() and vidioc_s_std() change the device-wide

dev->width / dev->norm but only refuse the change when the *video* queue

(dev->vidq) is busy. The VBI queue (dev->vbiq) shares that same geometry:

cx231xx_init_vbi_isoc() latches dma_q->lines_per_field from dev->norm,

the VBI videobuf2 plane is sized from dev->width / dev->norm in

vbi_queue_setup() and vbi_buf_prepare(), and cx231xx_do_vbi_copy() then

recomputes the destination offset from the *live* dev->width and the

latched lines_per_field on every URB completion:

offset = lines_completed * (dev->width << 1) + ...;

if (dma_q->current_field == 2)

offset += dev->width * 2 * dma_q->lines_per_field;

memcpy(plane + offset, p_buffer, lencopy);

Because the VBI node shares video_ioctl_ops with the video node, an

application can size a small VBI plane (REQBUFS/QBUF with a small width,

or with the NTSC standard), then enlarge dev->width (or switch dev->norm

to PAL) through the video node while the VBI stream is running -- the

change is allowed because only dev->vidq is checked -- and let the device

deliver a field-2 VBI payload. cx231xx_do_vbi_copy() now computes the

offset with the larger geometry and memcpy()s past the end of the smaller

plane that was already allocated, a heap out-of-bounds write whose offset

is attacker-chosen and whose contents come from the device. The

per-field guard in cx231xx_copy_vbi_line() does not help: it bounds the

copy against the latched lines_per_field, not the plane's real capacity,

and vb2 does not re-run buf_prepare() for an already prepared buffer.

Refuse the format/standard change when the VBI queue is busy as well, so

the geometry cannot change underneath an allocated VBI buffer. (NVD)

What to Do

Monitor Linux's web page for any future patch releases.

References