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CVE-2026-90248

net/sched: cls_api: fix teardown of an adopted proto on insert-race loss

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 5.15.221, 6.1.188, 6.6.157, 6.12.110, 6.18.52, and 1 more
None on Exploit-DB, Metasploit or GitHub

Summary

In the Linux kernel, the following vulnerability has been resolved: net/sched: cls_api: fix teardown of an adopted proto on insert-race loss In tc_new_tfilter() the create branch sets tp_created = 1 before calling tcf_chain_tp_insert_unique(). When the caller loses the race (another request inserted a proto at the same chain/prio first), insert_unique() destroys the caller's own tp_new and returns the winner's proto with an extra reference. tp_created was never cleared, so the loser's errout path treated the winner's live proto as its own and called tcf_chain_tp_delete_empty() on it, silently unlinking an active classifier that the winning request already advertised via RTM_NEWTFILTER. Track the outcome of the insert step in a single tri-state variable so each errout path reacts correctly: • TP_NOT_CREATED: no proto created; pursue the old path. • TP_CREATED: proto inserted successfully; same code path as before. • TP_NOT_OWNED: New - lost the insert race; tp is another request's proto (chain ref already released by tp_new's destroy) Both errout reactions are single expressions derived from the state. This fix is motivated by the Sashiko's automated review of Patch (net/sched: cls_api: Always acquire rtnl_lock when destroying locked classifiers) [1][2]. The review identified the silent-unlink behaviour of an adopted proto's teardown when a request loses the tcf_chain_tp_insert_unique() race. [1] https://sashiko.dev/#/patchset/20260801125632.360365-1-jhs%40mojatatu.com [2] https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20260801125632.360365-1-jhs%40mojatatu.com

Timeline

  1. CVE published
  2. Record last updated

Affected versions

  • Linux Linux

    From 8b64678e0af8f4d62a40149baedebe78503a5255 · fixed in a68e664ddf16ecae6d769d6a2eb356f8abab75c9; From 8b64678e0af8f4d62a40149baedebe78503a5255 · fixed in df02b6dc136af45e92ee4c86f4aa6c9a60790b1e; From 8b64678e0af8f4d62a40149baedebe78503a5255 · fixed in bee2208276c8e0e40a249ffdcf6e5434a79a847c; From 8b64678e0af8f4d62a40149baedebe78503a5255 · fixed in 219c87aeefdcc8c1caf28cc99e9b361ce7393d3a; From 8b64678e0af8f4d62a40149baedebe78503a5255 · fixed in bbe2fd6d77df630356185406a97317f6aa6a92cf; From 8b64678e0af8f4d62a40149baedebe78503a5255 · fixed in dc8b33b819cb02a75936940c120aa669ad89942d; From 8b64678e0af8f4d62a40149baedebe78503a5255 · fixed in d4e359b3608a0e184bbe8d61a5c3b50d0831c44a

  • Linux Linux

    5.1

  • KernelLinux

    From 5.1.0 · fixed in 5.15.221; From 5.16.0 · fixed in 6.1.188; From 6.2.0 · fixed in 6.6.157; From 6.7.0 · fixed in 6.12.110; From 6.13.0 · fixed in 6.18.52; From 6.19.0 · fixed in 7.2.6

References 7

git.kernel.org