{"id":"CVE-2026-99159","published":"2026-10-28T11:17:36.160","lastModified":"2026-10-28T11:17:36.160","description":"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_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.","cvssScore":null,"cvssSeverity":null,"cvssVector":null,"cwes":[],"vendors":[],"products":[],"references":[{"url":"https://git.kernel.org/stable/c/25132363c723afc39aace8b098f547ab4a0ea759","tags":[]},{"url":"https://git.kernel.org/stable/c/2f1248b728b56d583ea454fedf239550c49f7b18","tags":[]},{"url":"https://git.kernel.org/stable/c/7469b3585ef5f65840d467d2caa811a9098c84b9","tags":[]}],"exploitRefs":[],"hasPoc":false,"ai":null}