{"id":"CVE-2026-98629","published":"2026-10-18T16:17:15.960","lastModified":"2026-10-19T10:19:27.130","description":"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 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.","cvssScore":null,"cvssSeverity":null,"cvssVector":null,"cwes":[],"vendors":[],"products":[],"references":[{"url":"https://git.kernel.org/stable/c/0a5f5d9e94dead312d32c366b917c64e552b72f7","tags":[]},{"url":"https://git.kernel.org/stable/c/0fac292d93fdb313099e98cce928b3a524c92c94","tags":[]},{"url":"https://git.kernel.org/stable/c/21fc07924e996e1e661268ca269c86b8d59d25b3","tags":[]},{"url":"https://git.kernel.org/stable/c/2f898f9ec7c73c5697ee462681e7ea6984ee1f3d","tags":[]},{"url":"https://git.kernel.org/stable/c/54a454c5e41f5e2cb70c8163140ce095c5d5eefd","tags":[]},{"url":"https://git.kernel.org/stable/c/f6696481eedfd5752b4b56eed715d0b0fe48b9c5","tags":[]}],"exploitRefs":[],"hasPoc":false,"ai":null}