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CVE PROGRAM SOURCE RECORDUnscored

CVE-2026-98629

net/sched: cls_u32: fix manual hash table handle IDR aliasing

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Status
Published
Published
Updated
Assigning organization
Linux

Description

In the Linux kernel, the following vulnerability has been resolved: net/sched: cls_u32: fix manual hash table handle IDR aliasing A u32 hash table created with an explicit handle ('tc filter add ... handle 801: u32 divisor N') keys its IDR entry on the raw handle, while the destroy paths free it under handle2id(handle). The two key domains disagree for handles in the 0x800..0xFFF htid range: handle2id() folds them back into the auto-allocated id space (1..0x7FF). A manual table therefore leaves its raw-keyed IDR entry unreachable on delete (a permanent leak), and its delete can drop the idr entry of an unrelated live auto table. A later auto allocation can then hand out a handle that aliases the live manual table; u32_lookup_ht() first-match routes lookups and TCA_U32_LINK for that htid to the wrong table. Key the divisor-path alloc on handle2id(handle) so allocation and removal share one key domain. A manual handle that maps onto an id already in use is rejected with -ENOSPC, and auto allocation skips ids held by live manual tables. Conditions to recreate: ip link add test0 type dummy tc qdisc add dev test0 clsact tc filter add dev test0 ingress protocol ip pref 1 \ handle 801: u32 divisor 16 tc filter add dev test0 ingress protocol ip pref 2 u32 divisor 16 tc -d filter show dev test0 ingress | grep 'fh 801:' # unpatched: two live tables with handle 0x80100000 (the pref 2 root # hnode is auto-allocated id 1); patched: the auto hnode takes id 2. Also tested with a poc with a live u32 table on the block, add/delete a manual table 'handle 901: u32 divisor 1' twice; unpatched, the re-add fails with -ENOSPC because the raw key leaked on the first delete.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Linux Linux

Default version status: unaffected

  • 9b2c3184e126b941dfa716b8128ed6db92a64e2f to < 21fc07924e996e1e661268ca269c86b8d59d25b3affected
  • 789f9963bd031c3a185605665b744912df8e7eda to < 0fac292d93fdb313099e98cce928b3a524c92c94affected
  • 73af53d82076bbe184d9ece9e14b0dc8599e6055 to < 54a454c5e41f5e2cb70c8163140ce095c5d5eefdaffected
  • 73af53d82076bbe184d9ece9e14b0dc8599e6055 to < f6696481eedfd5752b4b56eed715d0b0fe48b9c5affected
  • 73af53d82076bbe184d9ece9e14b0dc8599e6055 to < 2f898f9ec7c73c5697ee462681e7ea6984ee1f3daffected
  • 73af53d82076bbe184d9ece9e14b0dc8599e6055 to < 0a5f5d9e94dead312d32c366b917c64e552b72f7affected
  • 4403f9293ce9ecc2a55c688d84ee37e3ba0fc1a8affected
  • 6.1.119 to < 6.1.189affected
  • 6.6.63 to < 6.6.158affected
  • 6.11.10 to < 6.12affected

Linux Linux

Default version status: affected

  • 6.12affected
  • 0 to < 6.12unaffected
  • 6.1.189 to ≤ 6.1.*unaffected
  • 6.6.158 to ≤ 6.6.*unaffected
  • 6.12.112 to ≤ 6.12.*unaffected
  • 6.18.55 to ≤ 6.18.*unaffected
  • 7.2.9 to ≤ 7.2.*unaffected
  • 7.3 to ≤ *unaffected

References