{"id":"CVE-2026-99159","title":"ring-buffer: Fix the sub-buffer array base in rb_meta_subbuf_idx()","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nring-buffer: Fix the sub-buffer array base in rb_meta_subbuf_idx()\n\nOn a persistent ring buffer, rb_meta_subbuf_idx() can return an index one\nsub-buffer too high.  rb_s…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= b14d032973d4e6c36e025e96ea3437de53d072d9 < 2f1248b728b56d583ea454fedf239550c49f7b18","Linux >= b14d032973d4e6c36e025e96ea3437de53d072d9 < 7469b3585ef5f65840d467d2caa811a9098c84b9","Linux >= b14d032973d4e6c36e025e96ea3437de53d072d9 < 25132363c723afc39aace8b098f547ab4a0ea759","Linux 6.12"],"published":"2026-10-28","updated":"2026-10-28","sourceUpdated":"2026-10-28T10:35:12.520Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-99159","references":[{"url":"https://git.kernel.org/stable/c/2f1248b728b56d583ea454fedf239550c49f7b18"},{"url":"https://git.kernel.org/stable/c/7469b3585ef5f65840d467d2caa811a9098c84b9"},{"url":"https://git.kernel.org/stable/c/25132363c723afc39aace8b098f547ab4a0ea759"}],"tags":["cve.org"],"ingestedAt":"2026-10-28T11:09:40.410Z","slug":"CVE-2026-99159","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nring-buffer: Fix the sub-buffer array base in rb_meta_subbuf_idx()\n\nOn a persistent ring buffer, rb_meta_subbuf_idx() can return an index one\nsub-buffer too high.  rb_setup_ids_meta_page() then fills subbuf_ids[]\nshifted by one and leaves subbuf_ids[0] NULL, which __rb_map_vma()\ndereferences when userspace maps trace_pipe_raw.  rb_update_meta_reader()\nwrites two such indices into meta->buffers[], which rb_cpu_meta_valid()\nwould reject on the next boot, discarding the previous boot's trace.\n\nA CPU's sub-buffer array starts after its meta header and the nr_subbufs\nintegers that follow, aligned up to a sub-buffer.  rb_meta_subbuf_idx()\ninverts that calculation but skips only the integers, not the header, so\nits base is one sub-buffer low whenever the omitted header size crosses\nthe alignment boundary.\n\nInvert the calculation with rb_subbufs_from_meta() rather than repeating\nit.  rb_range_buffer() maps an index back to an address through the same\nhelper, so the two directions can no longer disagree.\n\n## Affected\n\n- `Linux >= b14d032973d4e6c36e025e96ea3437de53d072d9 < 2f1248b728b56d583ea454fedf239550c49f7b18`\n- `Linux >= b14d032973d4e6c36e025e96ea3437de53d072d9 < 7469b3585ef5f65840d467d2caa811a9098c84b9`\n- `Linux >= b14d032973d4e6c36e025e96ea3437de53d072d9 < 25132363c723afc39aace8b098f547ab4a0ea759`\n- `Linux 6.12`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}