CVE-2025-38594

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

iommu/vt-d: Fix UAF on sva unbind with pending IOPFs

Commit 17fce9d2336d (iommu/vt-d: Put iopf enablement in domain attach path) disables IOPF on device by removing the device from its IOMMUs IOPF queue when the last IOPF-capable domain is detached from the device. Unfortunately, it did this in a wrong place where there are still pending IOPFs. As a result, a use-after-free error is potentially triggered and eventually a kernel panic with a kernel trace similar to the following:

refcount_t: underflow; use-after-free. WARNING: CPU: 3 PID: 313 at lib/refcount.c:28 refcount_warn_saturate+0xd8/0xe0 Workqueue: iopf_queue/dmar0-iopfq iommu_sva_handle_iopf Call Trace: iopf_free_group+0xe/0x20 process_one_work+0x197/0x3d0 worker_thread+0x23a/0x350 ? rescuer_thread+0x4a0/0x4a0 kthread+0xf8/0x230 ? finish_task_switch.isra.0+0x81/0x260 ? kthreads_online_cpu+0x110/0x110 ? kthreads_online_cpu+0x110/0x110 ret_from_fork+0x13b/0x170 ? kthreads_online_cpu+0x110/0x110 ret_from_fork_asm+0x11/0x20 —[ end trace 0000000000000000 ]—

The intel_pasid_tear_down_entry() function is responsible for blocking hardware from generating new page faults and flushing all in-flight ones. Therefore, moving iopf_for_domain_remove() after this function should resolve this.

Weakness

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/c68332b7ee893292bba6e87d31ef2080c066c65d
• https://git.kernel.org/stable/c/f0b9d31c6edd50a6207489cd1bd4ddac814b9cd2