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CVE-2026-89894

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

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.110, and 2 more
None on Exploit-DB, Metasploit or GitHub

Summary

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.

Timeline

  1. CVE published
  2. Record last updated

Affected versions

  • Linux Linux

    From 7c617138b8254a6bb60bfb5b8fc53eb8b3d6c3ab · fixed in aa3314506deb9703bcf0e889db08959440228fbf; From 7c617138b8254a6bb60bfb5b8fc53eb8b3d6c3ab · fixed in 90d50648af36a1fbf5dbc99238de6fd0e58a13e0; From 7c617138b8254a6bb60bfb5b8fc53eb8b3d6c3ab · fixed in a5dd3d7fba358ff9486f3f51b2a9038348c0970a; From 7c617138b8254a6bb60bfb5b8fc53eb8b3d6c3ab · fixed in 54ac6df8b8d97eddc3ae97fd2045bdedc8541b6d; From 7c617138b8254a6bb60bfb5b8fc53eb8b3d6c3ab · fixed in 1d1079db8d1807e259a1d2679ed314949797aad9; From 7c617138b8254a6bb60bfb5b8fc53eb8b3d6c3ab · fixed in 7087bef6510c7df5df0b19192633b8ecc0f33a6f; From 7c617138b8254a6bb60bfb5b8fc53eb8b3d6c3ab · fixed in a636c72c7f522d984fa498fc0631f33a2d0be3fd; From 7c617138b8254a6bb60bfb5b8fc53eb8b3d6c3ab · fixed in 627a121c15fe05a541f44d86016294b80bada75d

  • Linux Linux

    5.5

  • KernelLinux

    From 5.5.0 · fixed in 5.10.270; From 5.11.0 · fixed in 5.15.221; From 5.16.0 · fixed in 6.1.188; From 6.2.0 · fixed in 6.6.157; From 6.7.0 · fixed in 6.12.110; From 6.13.0 · fixed in 6.18.51; From 6.19.0 · fixed in 7.2.5

References 8

git.kernel.org