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CVE PROGRAM SOURCE RECORD7.8 High

CVE-2026-89894

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

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Status
Published
Published
Updated
Assigning organization
Linux

Description

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.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Linux Linux

Default version status: unaffected

  • 7c617138b8254a6bb60bfb5b8fc53eb8b3d6c3ab to < aa3314506deb9703bcf0e889db08959440228fbfaffected
  • 7c617138b8254a6bb60bfb5b8fc53eb8b3d6c3ab to < 90d50648af36a1fbf5dbc99238de6fd0e58a13e0affected
  • 7c617138b8254a6bb60bfb5b8fc53eb8b3d6c3ab to < a5dd3d7fba358ff9486f3f51b2a9038348c0970aaffected
  • 7c617138b8254a6bb60bfb5b8fc53eb8b3d6c3ab to < 54ac6df8b8d97eddc3ae97fd2045bdedc8541b6daffected
  • 7c617138b8254a6bb60bfb5b8fc53eb8b3d6c3ab to < 1d1079db8d1807e259a1d2679ed314949797aad9affected
  • 7c617138b8254a6bb60bfb5b8fc53eb8b3d6c3ab to < 7087bef6510c7df5df0b19192633b8ecc0f33a6faffected
  • 7c617138b8254a6bb60bfb5b8fc53eb8b3d6c3ab to < a636c72c7f522d984fa498fc0631f33a2d0be3fdaffected
  • 7c617138b8254a6bb60bfb5b8fc53eb8b3d6c3ab to < 627a121c15fe05a541f44d86016294b80bada75daffected

Linux Linux

Default version status: affected

  • 5.5affected
  • 0 to < 5.5unaffected
  • 5.10.270 to ≤ 5.10.*unaffected
  • 5.15.221 to ≤ 5.15.*unaffected
  • 6.1.188 to ≤ 6.1.*unaffected
  • 6.6.157 to ≤ 6.6.*unaffected
  • 6.12.110 to ≤ 6.12.*unaffected
  • 6.18.51 to ≤ 6.18.*unaffected
  • 7.2.5 to ≤ 7.2.*unaffected
  • 7.3 to ≤ *unaffected

References