CVE-2026-53248

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

net: airoha: Fix use-after-free in metadata dst teardown

airoha_metadata_dst_free() runs metadata_dst_free() which frees the metadata_dst with kfree() immediately, bypassing the RCU grace period. In the RX path, skb_dst_set_noref() sets a non-refcounted pointer from the skb to the metadata_dst. This function requires RCU read-side protection and the dst must remain valid until all RCU readers complete. Since metadata_dst_free() calls kfree() directly, an use-after-free can occur if any skb still holds a noref pointer to the dst when the driver tears it down. Replace metadata_dst_free() with dst_release() which properly goes through the refcount path: when the refcount drops to zero, it schedules the actual free via call_rcu_hurry(), ensuring all RCU readers have completed before the memory is freed.

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 Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.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/4b5a574e033e66d2131eff1c18feef8d8643c67e
• https://git.kernel.org/stable/c/6f829e2c17a53a35321268339cd252aff6d6d723
• https://git.kernel.org/stable/c/b38cae85d1c45ff189d7ecb6ac36f41cdc3d84d0