{"id":"CVE-2026-89501","state":"PUBLISHED","title":"ring-buffer: Hold cpu_buffer::lock when resizing a subbuf","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nring-buffer: Hold cpu_buffer::lock when resizing a subbuf\n\nBecause, ring_buffer_subbuf_order_set() can clear cpu_buffer->free_page,\nhold cpu_buffer->lock to prevent races with\nring_buffer_alloc_read_page() and ring_buffer_free_read_page().","publishedAt":"2026-09-11T19:43:50.063Z","updatedAt":"2026-10-19T08:47:52.839Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"8e7b58c27b3c567316a51079b375b846f9223bba","status":"affected","lessThan":"8a496aaa3da6e8d545896c2370c7e617cc931ae2","versionType":"git"},{"version":"8e7b58c27b3c567316a51079b375b846f9223bba","status":"affected","lessThan":"6fcb0b745a0b80df62eae4a93ce52a2d061f4ac2","versionType":"git"},{"version":"8e7b58c27b3c567316a51079b375b846f9223bba","status":"affected","lessThan":"bf242baf58de03467f226c8e29554c9495dca7fc","versionType":"git"},{"version":"8e7b58c27b3c567316a51079b375b846f9223bba","status":"affected","lessThan":"24974bd0da1b47fd56c975533ead50abf754e74d","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/trace/ring_buffer.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.8","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.8","versionType":"semver"},{"version":"6.12.109","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.50","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.4","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/trace/ring_buffer.c"]}],"references":["https://git.kernel.org/stable/c/8a496aaa3da6e8d545896c2370c7e617cc931ae2","https://git.kernel.org/stable/c/6fcb0b745a0b80df62eae4a93ce52a2d061f4ac2","https://git.kernel.org/stable/c/bf242baf58de03467f226c8e29554c9495dca7fc","https://git.kernel.org/stable/c/24974bd0da1b47fd56c975533ead50abf754e74d"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:26.108Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/89xxx/CVE-2026-89501.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-89501","state":"PUBLISHED","datePublished":"2026-09-11T19:43:50.063Z","dateUpdated":"2026-10-19T08:47:52.839Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-11T19:38:34.715Z"},"containers":{"cna":{"title":"ring-buffer: Hold cpu_buffer::lock when resizing a subbuf","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nring-buffer: Hold cpu_buffer::lock when resizing a subbuf\n\nBecause, ring_buffer_subbuf_order_set() can clear cpu_buffer->free_page,\nhold cpu_buffer->lock to prevent races with\nring_buffer_alloc_read_page() and ring_buffer_free_read_page()."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"8e7b58c27b3c567316a51079b375b846f9223bba","status":"affected","lessThan":"8a496aaa3da6e8d545896c2370c7e617cc931ae2","versionType":"git"},{"version":"8e7b58c27b3c567316a51079b375b846f9223bba","status":"affected","lessThan":"6fcb0b745a0b80df62eae4a93ce52a2d061f4ac2","versionType":"git"},{"version":"8e7b58c27b3c567316a51079b375b846f9223bba","status":"affected","lessThan":"bf242baf58de03467f226c8e29554c9495dca7fc","versionType":"git"},{"version":"8e7b58c27b3c567316a51079b375b846f9223bba","status":"affected","lessThan":"24974bd0da1b47fd56c975533ead50abf754e74d","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/trace/ring_buffer.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.8","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.8","versionType":"semver"},{"version":"6.12.109","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.50","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.4","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/trace/ring_buffer.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/8a496aaa3da6e8d545896c2370c7e617cc931ae2"},{"url":"https://git.kernel.org/stable/c/6fcb0b745a0b80df62eae4a93ce52a2d061f4ac2"},{"url":"https://git.kernel.org/stable/c/bf242baf58de03467f226c8e29554c9495dca7fc"},{"url":"https://git.kernel.org/stable/c/24974bd0da1b47fd56c975533ead50abf754e74d"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The bug is reached only via local tracefs syscalls: write() to buffer_subbuf_size_kb (ring_buffer_subbuf_order_set) racing with read()/close() on per_cpu/*/trace_pipe_raw (ring_buffer_alloc_read_page and ring_buffer_free_read_page). No network, adjacent-radio, or physical path reaches this free_page steal.\nAC:L - The attacker controls both sides of the race: one thread toggles buffer_subbuf_size_kb to copy and NULL cpu_buffer->free_page without cpu_buffer->lock, while another reads or closes trace_pipe_raw, which takes or caches that page under the lock. Success does not depend on an uninfluenced victim state.\nPR:L - tracing_check_open_get_tr() enforces only LOCKDOWN_TRACEFS and DAC with no capable() check. buffer_subbuf_size_kb and trace_pipe_raw are mode 0640 and are routinely delegated via tracefs gid=/mode= to tracing-group members on Android/Perfetto, ChromeOS, and developer kernels, matching prior CNA tracefs UAF scores.\nUI:N - Exploitation uses the attacker’s own tracefs file descriptors and threads (open/read/close trace_pipe_raw while writing buffer_subbuf_size_kb). No separate victim mount, click, or configuration action is required.\nS:U - The use-after-free and double-free corrupt kernel ring-buffer pages and metadata within the same OS security authority. This enables local privilege escalation but does not cross VM, IOMMU, container-hypervisor, or hardware trust boundaries.\nC:H - ring_buffer_subbuf_order_set() can free the cached free_page after alloc_read_page has already claimed it, including after ring_buffer_read_page swaps it into the live reader page. Recycled heap contents are then copied to userspace via tracing_buffers_read, giving a high-impact disclosure primitive.\nI:H - The same race double-frees the page or installs a freed page as the live ring-buffer reader page, so later tracing writes and free_read_page hit attacker-reclaimable heap. This UAF/double-free is exploitable for arbitrary kernel writes and control-flow hijack, not merely a crash.\nA:H - Concurrent free of a still-in-use reader or spare page corrupts ring-buffer lists and causes kernel oops/panic on UAF or double-free. The attacker can retrigger the race at will through repeated subbuf resizes and raw-buffer reads."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-19T08:47:52.839Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.8","versionEndExcluding":"6.12.109"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.8","versionEndExcluding":"6.18.50"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.8","versionEndExcluding":"7.2.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.8","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}