CVE-2026-99218

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CVE-2026-99218

Summary: coredump: hold RCU while releasing parked threads

Details: In the Linux kernel, the following vulnerability has been resolved: coredump: hold RCU while releasing parked threads coredump_finish() releases the parked threads by clearing ->task in their core_thread entry and calling wake_up_process() on each of them. It does that without holding a reference on the task and without being inside rcu. But calling wake_up_process(task) without rcu here isn't safe. A parked thread doesn't need that wakeup to leave. A spurious wakeup or a preemption after the store is enough for the task to go away. So if the coredump client is preempted between the store and wake_up_process() the thread can exit and be freed in the meantime and try_to_wake_up() takes pi_lock in freed memory. Hold rcu across the loop.

References: https://git.kernel.org/stable/c/0fce73efee40c65ce26641c5d93942462f9e8307, https://git.kernel.org/stable/c/16e94ed90b1b02398e044d41fd1db34828daa08e, https://git.kernel.org/stable/c/61d58591aa0188bf2463e263962256316ff8b576, https://git.kernel.org/stable/c/71146c437bae59e5280f657965dc6d006ee3989b, https://git.kernel.org/stable/c/a0f09ff4c6b93312e565cfe75d76c3a551a3ec4c, https://git.kernel.org/stable/c/b0eca0edddf4c1dbaf6d1f6a8636b4235f5bc573, https://git.kernel.org/stable/c/fd0fbe84312fda2fc187428c92c50b7d03a9d24c, https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/99xxx/CVE-2026-99218.json, https://nvd.nist.gov/vuln/detail/CVE-2026-99218, https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git