{"id":"CVE-2026-80876","title":"ring-buffer: Fix event length with forced 8-byte alignment","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nring-buffer: Fix event length with forced 8-byte alignment\n\nWhen RB_FORCE_8BYTE_ALIGNMENT is true, rb_calculate_event_length()\nreserves the space of event->array[0] for…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 2271048d1b3b0aabf83d25b29c20646dcabedc05 < 7c9f0ccf9f04142458d2ac3d39414f4acae242f0","Linux >= 2271048d1b3b0aabf83d25b29c20646dcabedc05 < 24c3fa71f9947b0e1f3b954db1b769b44140192e","Linux >= 2271048d1b3b0aabf83d25b29c20646dcabedc05 < 14057268e79654c3e8ea2c9b5204cb9644b2964d","Linux >= 2271048d1b3b0aabf83d25b29c20646dcabedc05 < dbcb8635b1eb7603818591cf745c7b1d714f7ac6","Linux >= 2271048d1b3b0aabf83d25b29c20646dcabedc05 < cfada73fabe2ccc06ec77fe2ceaa088689213326","Linux >= 2271048d1b3b0aabf83d25b29c20646dcabedc05 < ec5e96aee75d27779b9a860307679f13f33adb0c","Linux >= 2271048d1b3b0aabf83d25b29c20646dcabedc05 < 3a63a11897c7ba32d1be7a3fdbc48a8b01cf4992","Linux >= 2271048d1b3b0aabf83d25b29c20646dcabedc05 < c37e0a4b79a6bbb96ce5ffe279d7c001e20529e0","Linux 2.6.34"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-11-06T17:04:06.894723Z"},"published":"2026-09-04","updated":"2026-11-06","sourceUpdated":"2026-11-06T17:05:55.519Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-80876","references":[{"url":"https://git.kernel.org/stable/c/7c9f0ccf9f04142458d2ac3d39414f4acae242f0"},{"url":"https://git.kernel.org/stable/c/24c3fa71f9947b0e1f3b954db1b769b44140192e"},{"url":"https://git.kernel.org/stable/c/14057268e79654c3e8ea2c9b5204cb9644b2964d"},{"url":"https://git.kernel.org/stable/c/dbcb8635b1eb7603818591cf745c7b1d714f7ac6"},{"url":"https://git.kernel.org/stable/c/cfada73fabe2ccc06ec77fe2ceaa088689213326"},{"url":"https://git.kernel.org/stable/c/ec5e96aee75d27779b9a860307679f13f33adb0c"},{"url":"https://git.kernel.org/stable/c/3a63a11897c7ba32d1be7a3fdbc48a8b01cf4992"},{"url":"https://git.kernel.org/stable/c/c37e0a4b79a6bbb96ce5ffe279d7c001e20529e0"}],"tags":["cve.org"],"epss":0.0022,"epssPercentile":0.12541,"ingestedAt":"2026-11-06T18:00:12.531Z","slug":"CVE-2026-80876","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nring-buffer: Fix event length with forced 8-byte alignment\n\nWhen RB_FORCE_8BYTE_ALIGNMENT is true, rb_calculate_event_length()\nreserves the space of event->array[0] for placing the data length and\nrb_update_event() stores the data length in event->array[0]\naccordingly. As a result the whole event length will add extra 4 bytes\nfor sizeof(event.array[0]) unconditionally.\n\nBut ring_buffer_event_length() only subtracts the\nsizeof(event->array[0]) for events larger than RB_MAX_SMALL_DATA +\nsizeof(event->array[0]). As a result, small events on architectures\nwith RB_FORCE_8BYTE_ALIGNMENT=true report a data length that is 4\nbytes larger than expected.\n\nTo fix it, add the RB_FORCE_8BYTE_ALIGNMENT as a condition to subtract\nthe size of that length field whenever RB_FORCE_8BYTE_ALIGNMENT is\ntrue.\n\nThis issue is observed in a riscv64 kernel with\nCONFIG_HAVE_64BIT_ALIGNED_ACCESS set to y, when we run ftrace selftest\ntrace_marker_raw.tc, we get the weird log: for cases where the id is\n1..100, the number of data field is 8*N, but once id exceeds 100, the\nnumber of data field becomes 8*N+4:\n # 1 buf: 58 00 00 00 80 5e d1 63 (number of data field is 8*1)\n ...\n # a buf: 58 ...                  (number of data field is 8*2)\n ...\n # 64 buf: 58 ...                 (number of data field is 8*13)\n # 65 buf: 58 ...                 (number of data field is 8*13+4)\n\nAfter applying this change, the number of data field keeps being 8*N+4\nconsistently.\n\n## Affected\n\n- `Linux >= 2271048d1b3b0aabf83d25b29c20646dcabedc05 < 7c9f0ccf9f04142458d2ac3d39414f4acae242f0`\n- `Linux >= 2271048d1b3b0aabf83d25b29c20646dcabedc05 < 24c3fa71f9947b0e1f3b954db1b769b44140192e`\n- `Linux >= 2271048d1b3b0aabf83d25b29c20646dcabedc05 < 14057268e79654c3e8ea2c9b5204cb9644b2964d`\n- `Linux >= 2271048d1b3b0aabf83d25b29c20646dcabedc05 < dbcb8635b1eb7603818591cf745c7b1d714f7ac6`\n- `Linux >= 2271048d1b3b0aabf83d25b29c20646dcabedc05 < cfada73fabe2ccc06ec77fe2ceaa088689213326`\n- `Linux >= 2271048d1b3b0aabf83d25b29c20646dcabedc05 < ec5e96aee75d27779b9a860307679f13f33adb0c`\n- `Linux >= 2271048d1b3b0aabf83d25b29c20646dcabedc05 < 3a63a11897c7ba32d1be7a3fdbc48a8b01cf4992`\n- `Linux >= 2271048d1b3b0aabf83d25b29c20646dcabedc05 < c37e0a4b79a6bbb96ce5ffe279d7c001e20529e0`\n- `Linux 2.6.34`\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":[]}