CVE-2026-53247net: ethernet: mtk_eth_soc: Fix use-after-free in metadata dst teardown

Official description

In the Linux kernel, the following vulnerability has been resolved: net: ethernet: mtk_eth_soc: Fix use-after-free in metadata dst teardown mtk_free_dev() calls 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, a 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.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/72775977e89c25c99ee84d2c5baa3f86a8ba5cb4
• https://git.kernel.org/stable/c/459c6f35c58cf0fd5247e55d73ddaa29571d9b7e
• https://git.kernel.org/stable/c/e634408d2b0cd939cfe019398a21fb47b7a8ffe3
• https://git.kernel.org/stable/c/2d86aeb46d5f69c704065a8c69822582787272a1
• https://git.kernel.org/stable/c/80df409e1a483676826a6c66e693dba6ac507751