CVE-2026-93137

Summary

In the Linux kernel, the following vulnerability has been resolved:

bpf: Fix use-after-free on mm_struct in bpf_find_vma()

bpf_find_vma() reads task->mm and calls mmap_read_trylock(mm) without holding a reference on the mm. On a foreign task, a concurrent exit_mm() can free the mm_struct between the lockless read and the trylock, resulting in a use-after-free. mm_struct is not SLAB_TYPESAFE_BY_RCU.

For the current task, task->mm is stable. For a foreign task, pin the mm under task->alloc_lock and release it with mmput_async(), mirroring commit d8e27d2d22b6 ("bpf: fix mm lifecycle in open-coded task_vma iterator"). Use spin_trylock() instead of get_task_mm() so BPF context does not block on alloc_lock. Reject irqs-disabled contexts and !CONFIG_MMU on the foreign-task path because dropping the mm reference is not safe there.

Race:

CPU0 (BPF program) CPU1 (exiting task) ============================ ========================== bpf_find_vma(foreign_task): mm = task->mm exit_mm(): task->mm = NULL mmput(mm) -> frees mm_struct mmap_read_trylock(mm) // UAF on mm

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/db347840d6b6ee9bb9b8e4a985d4b4419f9f3200
• https://git.kernel.org/stable/c/8e1101fc4118019a69c96ced4aec93164f89cbd5
• https://git.kernel.org/stable/c/c7ad910e987008e125eeff448892e86852173384
• https://git.kernel.org/stable/c/86d54cf069fc5ae2e111c87933bebf6eb527978e
• https://git.kernel.org/stable/c/2b2a903bee56d312539046d9defa8023eec94760
• https://git.kernel.org/stable/c/47b079e2117a2ee52e21f8b72935900c702fc0b5

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