# CVE-2026-90302: ocfs2: synchronize heartbeat callbacks with o2net teardown > A race condition in the Linux kernel OCFS2 filesystem allows a use-after-free during heartbeat teardown, potentially leading to system crashes or code execution. - **Severity:** Not scored - **Exploited in the wild:** Not known - **Login needed:** An administrator - **Attackable:** Local or same network only - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 17 Sep 2026 - **Updated:** 19 Oct 2026 - **Also known as:** AZL-102873, BELL-CVE-2026-90302, DEBIAN-CVE-2026-90302, GHSA-jpvp-fw99-v7cq, UBUNTU-CVE-2026-90302 ## What is CVE-2026-90302? CVE-2026-90302 is an use after free vulnerability in Linux, published on 17 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim. ### Official description In the Linux kernel, the following vulnerability has been resolved: ocfs2: synchronize heartbeat callbacks with o2net teardown Patch series "ocfs2: harden heartbeat teardown races". This series fixes two OCFS2 heartbeat/o2net teardown races found by KASAN. This patch (of 2): Heartbeat callbacks stay registered while configfs local-node teardown enters o2net_stop_listening(). A node-down event can still run through o2net_disconnect_node() and o2net_set_nn_state() while teardown is destroying o2net_wq, so the later queue/flush operations can hit a dead workqueue. KASAN has caught this as a slab-use-after-free in __queue_work() with the call chain: KASAN slab-use-after-free in __queue_work+0x56/0xa90 Read of size 4 Call trace: dump_stack_lvl+0x66/0xa0 print_report+0xce/0x630 __queue_work+0x56/0xa90 srso_alias_return_thunk+0x5/0xfbef5 __virt_addr_valid+0x19f/0x330 kasan_report+0xe0/0x110 __queue_delayed_work+0x58/0x1e0 queue_delayed_work_on+0xb4/0xc0 o2net_set_nn_state+0x467/0x840 o2net_disconnect_node+0x7b/0xe0 o2net_hb_node_down_cb+0x54/0x60 o2hb_run_event_list+0x236/0x2d0 o2hb_check_slot+0xad4/0xbc0 lock_release+0xc8/0x290 o2hb_check_slot+0x9ea/0xbc0 trace_hardirqs_on+0x18/0x130 o2hb_do_disk_heartbeat+0x646/0xb30 (fs/ocfs2/cluster/heartbeat.c:1079) __lock_acquire+0x466/0x2260 lockdep_hardirqs_on_prepare+0xea/0x1a0 ktime_get_with_offset+0xe9/0x230 o2hb_thread+0x14e/0x770 kthread+0x1ad/0x1f0 ret_from_fork+0x3c9/0x540 __switch_to+0x2e9/0x730 ret_from_fork_asm+0x1a/0x30 Allocated by task stack: kasan_save_stack+0x33/0x60 kasan_save_track+0x14/0x30 __kasan_kmalloc+0xaa/0xb0 __kmalloc_noprof+0x292/0x760 __alloc_workqueue+0x736/0xc60 alloc_workqueue_noprof+0xb1/0x110 o2net_start_listening+0xe5/0x430 o2nm_node_local_store+0x184/0x310 configfs_write_iter+0x18a/0x210 vfs_write+0x469/0x810 ksys_write+0xd2/0x170 do_syscall_64+0x115/0x6a0 (arch/x86/entry/syscall_64.c:87) entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task stack: kasan_save_stack+0x33/0x60 kasan_save_track+0x14/0x30 kasan_save_free_info+0x3b/0x60 __kasan_slab_free+0x5f/0x80 kfree+0x313/0x590 rcu_core+0x4f4/0x1320 handle_softirqs+0x156/0x660 queue_delayed_work_on o2net_set_nn_state o2net_disconnect_node o2net_hb_node_down_cb o2hb_run_event_list Keep heartbeat callbacks registered so quorum state still tracks node state, but stop them from driving o2net reconnect/disconnect work once local teardown starts. Mark the transport offline before destroying o2net_wq, wait for any in-flight heartbeat callback to finish, and delay bring-up replay until the new local node is published through o2nm_this_node(). The replay also has to stay serialized with heartbeat callback delivery. Otherwise a live-node snapshot can be copied, a real hb_down callback can install -ENOTCONN for a peer, and the stale replay can call o2net_hb_node_up() for that same peer and queue reconnect work even though heartbeat is already down. The buggy scenario involves two paths, with each column showing the order within that path: local-node teardown: heartbeat node-down callback: 1. configfs local-off enters 1. o2hb_run_event_list() invokes o2net_stop_listening(). o2net_hb_node_down_cb(). 2. teardown heads for 2. the callback reaches destroy_workqueue(o2net_wq). o2net_disconnect_node() and o2net_set_nn_state(). 3. teardown destroys and NULLs 3. the callback flushes or queues o2net_wq. work through o2net_wq. ## Which versions are affected by CVE-2026-90302? ## How do I fix CVE-2026-90302? Apply the vendor's patch. ## Is CVE-2026-90302 being exploited? There is no known exploitation of CVE-2026-90302 in the wild and no public exploit code. ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-90302 and fix it if it is affected. What it is: CVE-2026-90302 is an use after free vulnerability in Linux, published on 17 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim. Exploitation: There is no known exploitation of CVE-2026-90302 in the wild and no public exploit code. Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page. Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2026-90302/ (Markdown: https://insights.sbomify.com/CVE-2026-90302/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90302 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90302 - OSV: https://osv.dev/vulnerability/CVE-2026-90302 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-90302/ Summaries are generated and may contain mistakes; the official description above is the record.