{"id":"CVE-2026-89894","summary":"media: cx231xx: reject geometry changes while the VBI queue is busy","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nmedia: cx231xx: reject geometry changes while the VBI queue is busy\n\nvidioc_s_fmt_vid_cap() and vidioc_s_std() change the device-wide\ndev-\u003ewidth / dev-\u003enorm but only refuse the change when the *video* queue\n(dev-\u003evidq) is busy. The VBI queue (dev-\u003evbiq) shares that same geometry:\ncx231xx_init_vbi_isoc() latches dma_q-\u003elines_per_field from dev-\u003enorm,\nthe VBI videobuf2 plane is sized from dev-\u003ewidth / dev-\u003enorm in\nvbi_queue_setup() and vbi_buf_prepare(), and cx231xx_do_vbi_copy() then\nrecomputes the destination offset from the *live* dev-\u003ewidth and the\nlatched lines_per_field on every URB completion:\n\n\toffset = lines_completed * (dev-\u003ewidth \u003c\u003c 1) + ...;\n\tif (dma_q-\u003ecurrent_field == 2)\n\t\toffset += dev-\u003ewidth * 2 * dma_q-\u003elines_per_field;\n\tmemcpy(plane + offset, p_buffer, lencopy);\n\nBecause the VBI node shares video_ioctl_ops with the video node, an\napplication can size a small VBI plane (REQBUFS/QBUF with a small width,\nor with the NTSC standard), then enlarge dev-\u003ewidth (or switch dev-\u003enorm\nto PAL) through the video node while the VBI stream is running -- the\nchange is allowed because only dev-\u003evidq is checked -- and let the device\ndeliver a field-2 VBI payload. cx231xx_do_vbi_copy() now computes the\noffset with the larger geometry and memcpy()s past the end of the smaller\nplane that was already allocated, a heap out-of-bounds write whose offset\nis attacker-chosen and whose contents come from the device. The\nper-field guard in cx231xx_copy_vbi_line() does not help: it bounds the\ncopy against the latched lines_per_field, not the plane's real capacity,\nand vb2 does not re-run buf_prepare() for an already prepared buffer.\n\nRefuse the format/standard change when the VBI queue is busy as well, so\nthe geometry cannot change underneath an allocated VBI buffer.","modified":"2026-09-18T03:48:33.766878868Z","published":"2026-09-16T10:31:56.101Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89894.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/1d1079db8d1807e259a1d2679ed314949797aad9"},{"type":"WEB","url":"https://git.kernel.org/stable/c/54ac6df8b8d97eddc3ae97fd2045bdedc8541b6d"},{"type":"WEB","url":"https://git.kernel.org/stable/c/627a121c15fe05a541f44d86016294b80bada75d"},{"type":"WEB","url":"https://git.kernel.org/stable/c/7087bef6510c7df5df0b19192633b8ecc0f33a6f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/90d50648af36a1fbf5dbc99238de6fd0e58a13e0"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a5dd3d7fba358ff9486f3f51b2a9038348c0970a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a636c72c7f522d984fa498fc0631f33a2d0be3fd"},{"type":"WEB","url":"https://git.kernel.org/stable/c/aa3314506deb9703bcf0e889db08959440228fbf"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89894.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89894"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"7c617138b8254a6bb60bfb5b8fc53eb8b3d6c3ab"},{"fixed":"aa3314506deb9703bcf0e889db08959440228fbf"},{"fixed":"90d50648af36a1fbf5dbc99238de6fd0e58a13e0"},{"fixed":"a5dd3d7fba358ff9486f3f51b2a9038348c0970a"},{"fixed":"54ac6df8b8d97eddc3ae97fd2045bdedc8541b6d"},{"fixed":"1d1079db8d1807e259a1d2679ed314949797aad9"},{"fixed":"7087bef6510c7df5df0b19192633b8ecc0f33a6f"},{"fixed":"a636c72c7f522d984fa498fc0631f33a2d0be3fd"},{"fixed":"627a121c15fe05a541f44d86016294b80bada75d"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89894.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.5.0"},{"fixed":"5.10.270"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.221"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.188"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.157"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.110"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.51"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.5"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89894.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}