In the Linux kernel, the following vulnerability has been resolved:
net: ibm: emac: Fix use-after-free during device removal
The driver was using devm_register_netdev() which causes unregister_netdev() to be deferred until the devres cleanup phase, which runs after emac_remove() returns. This creates a use-after-free window where:
- emac_remove() is called, which tears down hardware (cancels work, detaches
- emac_remove() returns
- devres cleanup runs and finally calls unregister_netdev()
During step 3, the network stack might still process packets, triggering emac_irq(), emac_poll(), or other handlers that access now-freed hardware resources (dev->emacp, dev->mal, etc.).
Fix this by replacing devm_register_netdev() with manual register_netdev() and calling unregister_netdev() at the beginning of emac_remove(), before any hardware teardown. This ensures the network device is fully stopped and unregistered before hardware resources are released.
The change is safe because:
- dev->ndev is assigned very early in probe (before any error paths that
- platform_set_drvdata() is only called after successful registration, so
- unregister_netdev() is idempotent and safe to call on any registered device