{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-98104", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-25T10:25:14.315Z", "datePublished": "2026-09-25T10:35:54.544Z", "dateUpdated": "2026-10-19T09:13:56.808Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T09:13:56.808Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: cls_u32: fix duplicate handle when node ID pool is exhausted\n\ngen_new_kid() falls back to returning max (htid | 0xFFF) when both\nidr_alloc_u32() ranges are full, instead of reporting an error.\nu32_change() trusts that value and inserts a new knode with a handle\nthat is already live in the hash table, breaking handle uniqueness\nwithin the table's node ID space.\n\nThe handle was never reserved in ht->handle_idr, so every later error\npath that does idr_remove(&ht->handle_idr, handle) removes the\nreservation of a different, live knode, which is then reused — one\nfailed add compounds into further duplicates.\n\nThe 4095 limit is per (table, bucket) — ht->handle_idr is per hash\ntable and the range is derived from htid (bucketid), so a table with\ndivisor 256 can legitimately hold 256*4095 knodes.\n\nThe sibling helper gen_new_htid() has the same silent in-band failure:\nit returns 0 when the tp_c handle pool (1..0x7FF) is full, and\nu32_init() publishes the root hash table with handle 0 without\nchecking. Two root tables with handle 0 alias in u32_lookup_ht(),\nallowing cross-tcf_proto knode add/lookup/delete. Add the same\nexhaustion check that the divisor path already has.\n\nReturn an error so u32_change() fails with ENOSPC/ENOMEM when the\nnode ID space is exhausted, and so u32_init() fails with -ENOMEM\nwhen the hash table ID space is exhausted. The extack message\ndistinguishes pool exhaustion (-ENOSPC) from a transient allocation\nfailure (-ENOMEM).\n\nConditions to recreate the bug:\n- CONFIG_NET_SCHED=y, CONFIG_CLS_U32=y (or =m with module loaded)\n- Create a clsact qdisc on a device, then add 4095 u32 filters with\n auto-generated handles to fill the node ID space for the root hash\n table (single bucket). The 4096th auto-handle filter add triggers\n the duplicate handle (fh 800::fff reused). Reachable at Level 2\n (unshare -Urn, namespace-local CAP_NET_ADMIN).\n- For gen_new_htid: create 2047 u32 proto entries on the same block\n to fill the tp_c handle pool, then create one more. The root table\n gets handle 0 and aliases with other handle-0 root tables." } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/sched/cls_u32.c" ], "versions": [ { "version": "7801db8aec957fa6610efe0ee26a6c8bc0f1d73b", "lessThan": "f4ee13ed7f7b22dcd8287fcf477ae37bd84567da", "status": "affected", "versionType": "git" }, { "version": "7801db8aec957fa6610efe0ee26a6c8bc0f1d73b", "lessThan": "84223baf21bc9b008444ae9bc38d5fb91fe00b9d", "status": "affected", "versionType": "git" }, { "version": "7801db8aec957fa6610efe0ee26a6c8bc0f1d73b", "lessThan": "6890e28840bae4f6805e8de981c4ec8e12a4e064", "status": "affected", "versionType": "git" }, { "version": "7801db8aec957fa6610efe0ee26a6c8bc0f1d73b", "lessThan": "feab9261b537df4ebb8350e4779bc185373059fd", "status": "affected", "versionType": "git" }, { "version": "7801db8aec957fa6610efe0ee26a6c8bc0f1d73b", "lessThan": "f594f04268d01c5fdc975f3f51fc219ea2159ac6", "status": "affected", "versionType": "git" }, { "version": "7801db8aec957fa6610efe0ee26a6c8bc0f1d73b", "lessThan": "d7e7e98d23f42a92d9ab7e36302bd96bd9b33b5f", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/sched/cls_u32.c" ], "versions": [ { "version": "3.16", "status": "affected" }, { "version": "0", "lessThan": "3.16", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.189", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.158", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.111", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.53", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.7", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.16", "versionEndExcluding": "6.1.189" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.16", "versionEndExcluding": "6.6.158" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.16", "versionEndExcluding": "6.12.111" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.16", "versionEndExcluding": "6.18.53" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.16", "versionEndExcluding": "7.2.7" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.16", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/f4ee13ed7f7b22dcd8287fcf477ae37bd84567da" }, { "url": "https://git.kernel.org/stable/c/84223baf21bc9b008444ae9bc38d5fb91fe00b9d" }, { "url": "https://git.kernel.org/stable/c/6890e28840bae4f6805e8de981c4ec8e12a4e064" }, { "url": "https://git.kernel.org/stable/c/feab9261b537df4ebb8350e4779bc185373059fd" }, { "url": "https://git.kernel.org/stable/c/f594f04268d01c5fdc975f3f51fc219ea2159ac6" }, { "url": "https://git.kernel.org/stable/c/d7e7e98d23f42a92d9ab7e36302bd96bd9b33b5f" } ], "title": "net/sched: cls_u32: fix duplicate handle when node ID pool is exhausted", "x_generator": { "engine": "bippy-1.2.0" } } } }