{"id":"CVE-2026-98629","title":"net/sched: cls_u32: fix manual hash table handle IDR aliasing","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: cls_u32: fix manual hash table handle IDR aliasing\n\nA u32 hash table created with an explicit handle ('tc filter add ...\nhandle 801: u32 divisor N') keys its…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 9b2c3184e126b941dfa716b8128ed6db92a64e2f < 21fc07924e996e1e661268ca269c86b8d59d25b3","Linux >= 789f9963bd031c3a185605665b744912df8e7eda < 0fac292d93fdb313099e98cce928b3a524c92c94","Linux >= 73af53d82076bbe184d9ece9e14b0dc8599e6055 < 54a454c5e41f5e2cb70c8163140ce095c5d5eefd","Linux >= 73af53d82076bbe184d9ece9e14b0dc8599e6055 < f6696481eedfd5752b4b56eed715d0b0fe48b9c5","Linux >= 73af53d82076bbe184d9ece9e14b0dc8599e6055 < 2f898f9ec7c73c5697ee462681e7ea6984ee1f3d","Linux >= 73af53d82076bbe184d9ece9e14b0dc8599e6055 < 0a5f5d9e94dead312d32c366b917c64e552b72f7","Linux 4403f9293ce9ecc2a55c688d84ee37e3ba0fc1a8","Linux >= 6.1.119 < 6.1.189","Linux >= 6.6.63 < 6.6.158","Linux >= 6.11.10 < 6.12","Linux 6.12"],"published":"2026-10-18","updated":"2026-10-18","sourceUpdated":"2026-10-18T15:19:50.589Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-98629","references":[{"url":"https://git.kernel.org/stable/c/21fc07924e996e1e661268ca269c86b8d59d25b3"},{"url":"https://git.kernel.org/stable/c/0fac292d93fdb313099e98cce928b3a524c92c94"},{"url":"https://git.kernel.org/stable/c/54a454c5e41f5e2cb70c8163140ce095c5d5eefd"},{"url":"https://git.kernel.org/stable/c/f6696481eedfd5752b4b56eed715d0b0fe48b9c5"},{"url":"https://git.kernel.org/stable/c/2f898f9ec7c73c5697ee462681e7ea6984ee1f3d"},{"url":"https://git.kernel.org/stable/c/0a5f5d9e94dead312d32c366b917c64e552b72f7"}],"tags":["cve.org"],"ingestedAt":"2026-10-18T15:45:12.235Z","slug":"CVE-2026-98629","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: cls_u32: fix manual hash table handle IDR aliasing\n\nA u32 hash table created with an explicit handle ('tc filter add ...\nhandle 801: u32 divisor N') keys its IDR entry on the raw handle, while\nthe destroy paths free it under handle2id(handle). The two key domains\ndisagree for handles in the 0x800..0xFFF htid range:\nhandle2id() folds them back into the auto-allocated id space (1..0x7FF).\n\nA manual table therefore leaves its raw-keyed IDR entry unreachable on\ndelete (a permanent leak), and its delete can drop the idr entry of an\nunrelated live auto table. A later auto allocation can then hand out a\nhandle that aliases the live manual table; u32_lookup_ht() first-match\nroutes lookups and TCA_U32_LINK for that htid to the wrong table.\n\nKey the divisor-path alloc on handle2id(handle) so allocation and\nremoval share one key domain. A manual handle that maps onto an id\nalready in use is rejected with -ENOSPC, and auto allocation skips ids\nheld by live manual tables.\n\nConditions to recreate:\n  ip link add test0 type dummy\n  tc qdisc add dev test0 clsact\n  tc filter add dev test0 ingress protocol ip pref 1 \\\n          handle 801: u32 divisor 16\n  tc filter add dev test0 ingress protocol ip pref 2 u32 divisor 16\n  tc -d filter show dev test0 ingress | grep 'fh 801:'\n  # unpatched: two live tables with handle 0x80100000 (the pref 2 root\n  # hnode is auto-allocated id 1); patched: the auto hnode takes id 2.\n\nAlso tested with a poc with a live u32 table on the block, add/delete a manual\ntable 'handle 901: u32 divisor 1' twice; unpatched, the re-add fails with\n-ENOSPC because the raw key leaked on the first delete.\n\n## Affected\n\n- `Linux >= 9b2c3184e126b941dfa716b8128ed6db92a64e2f < 21fc07924e996e1e661268ca269c86b8d59d25b3`\n- `Linux >= 789f9963bd031c3a185605665b744912df8e7eda < 0fac292d93fdb313099e98cce928b3a524c92c94`\n- `Linux >= 73af53d82076bbe184d9ece9e14b0dc8599e6055 < 54a454c5e41f5e2cb70c8163140ce095c5d5eefd`\n- `Linux >= 73af53d82076bbe184d9ece9e14b0dc8599e6055 < f6696481eedfd5752b4b56eed715d0b0fe48b9c5`\n- `Linux >= 73af53d82076bbe184d9ece9e14b0dc8599e6055 < 2f898f9ec7c73c5697ee462681e7ea6984ee1f3d`\n- `Linux >= 73af53d82076bbe184d9ece9e14b0dc8599e6055 < 0a5f5d9e94dead312d32c366b917c64e552b72f7`\n- `Linux 4403f9293ce9ecc2a55c688d84ee37e3ba0fc1a8`\n- `Linux >= 6.1.119 < 6.1.189`\n- `Linux >= 6.6.63 < 6.6.158`\n- `Linux >= 6.11.10 < 6.12`\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":[]}