CVE-2026-53234

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:

1. emac_remove() is called, which tears down hardware (cancels work, detaches modules, unregisters from MAL)
2. emac_remove() returns
3. 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 could bypass emac_remove)
• platform_set_drvdata() is only called after successful registration, so emac_remove() only runs for fully registered devices
• unregister_netdev() is idempotent and safe to call on any registered device

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 Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.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/a0130d682222ae21afc395aead7cd2d87e1a8358
• https://git.kernel.org/stable/c/c09c2e236eef6f59e105f38a30f5439e6ccbcad7
• https://git.kernel.org/stable/c/c12584cd6078085d707266be864e7e1cc91d74e3
• https://git.kernel.org/stable/c/cf8e14db93eaecc4c0c58299be3b3183b0e53ed5