{"schema":"threatline.record/2","record":{"id":"CVE-2026-98789","aliases":[],"summary":"bpf: Fix objects stuck in free_by_rcu_ttrace","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix objects stuck in free_by_rcu_ttrace\n\ndo_call_rcu_ttrace() returns early when call_rcu_ttrace_in_progress is set\nand leaves the objects in free_by_rcu_ttrace. __free_rcu() frees\nwaiting_for_gp_ttrace only and clears the flag. Hence the objects that\nfree_bulk() or __free_by_rcu() added while RCU tasks trace GP was in flight\nstay in free_by_rcu_ttrace until free_bulk() or alloc_bulk() is called for\nthe same bpf_mem_cache again, which may never happen. The number of such\nobjects is not bounded.\n\nTurn call_rcu_ttrace_in_progress into three states:\n0 - idle\n1 - __free_rcu() is queued\n2 - __free_rcu() is queued and free_by_rcu_ttrace got more objects since\n\ndo_call_rcu_ttrace() sets 2. __free_rcu() does cmpxchg(1 -> 0) and starts\nthe next GP when it fails. It cannot clear the flag first and check\nfree_by_rcu_ttrace later, since bpf_mem_alloc_destroy() frees bpf_mem_cache\nwithout waiting for RCU callbacks when the flag is zero.\n\nNow __free_rcu() queues itself, so the one that didn't see 'draining' may\ndo call_rcu_tasks_trace() after rcu_barrier_tasks_trace() in\nfree_mem_alloc(). Queue it under rcu_read_lock() and do synchronize_rcu()\nbefore the barriers. Calling rcu_barrier_tasks_trace() twice works too, but\ncreating and destroying hash maps in a loop on many cpus slows down to one\nfree_mem_alloc() per GP and kworkers pile up.","categories":["Operating systems"],"product":"Linux","vendor":"Linux","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98789","source_modified_at":"2026-10-19T09:25:42.177Z","fetched_at":"2026-10-23T18:45:31.882637Z","product":"Linux","vendor":"Linux","versions":[{"version":"8d5a8011b35d387c490a5c977b1d9eb4798aa071","lessThan":"33d0a5d2fee06a51f2f056dd901296515912e954","status":"affected","versionType":"git"},{"version":"8d5a8011b35d387c490a5c977b1d9eb4798aa071","lessThan":"fbd97dd1d3ce32d32fb7be86acc3fdb7c04fa043","status":"affected","versionType":"git"}],"defaultStatus":"unaffected"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98789","source_modified_at":"2026-10-19T09:25:42.177Z","fetched_at":"2026-10-23T18:45:31.882637Z","product":"Linux","vendor":"Linux","versions":[{"version":"6.1","status":"affected"},{"version":"0","lessThan":"6.1","status":"unaffected","versionType":"semver"},{"version":"7.2.10","lessThanOrEqual":"7.2.*","status":"unaffected","versionType":"semver"},{"version":"7.3","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}],"defaultStatus":"affected"}],"fixed_versions":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98789","source_modified_at":"2026-10-19T09:25:42.177Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"Linux","ecosystem":null},"version":"33d0a5d2fee06a51f2f056dd901296515912e954","basis":"first unaffected version stated in the CVE record"}],"cvss":null,"severity":null,"kev":{"listed":false},"epss":{"probability":0.00155,"percentile":0.04323,"score_date":"2026-10-23"},"published_at":"2026-10-18T15:48:25.665Z","modified_at":"2026-10-19T09:25:42.177Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-98789","fetched_at":"2026-10-23T18:45:31.882637Z","source_modified_at":"2026-10-19T09:25:42.177Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-98789","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["CVE List","EPSS"],"references":[{"source":"CVE List","url":"https://git.kernel.org/stable/c/33d0a5d2fee06a51f2f056dd901296515912e954"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/fbd97dd1d3ce32d32fb7be86acc3fdb7c04fa043"}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":"product","confidence":"heuristic","reviewed":false},"change_timestamp":"2026-10-19T09:25:42.177Z","content_hash":"eb34a709ba82842584ad432386d014f44ec7d9cefbebb20924e13b8417272994"}}