CVE-2026-53234

Summary

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

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/cf8e14db93eaecc4c0c58299be3b3183b0e53ed5
• https://git.kernel.org/stable/c/c09c2e236eef6f59e105f38a30f5439e6ccbcad7
• https://git.kernel.org/stable/c/c12584cd6078085d707266be864e7e1cc91d74e3
• https://git.kernel.org/stable/c/a0130d682222ae21afc395aead7cd2d87e1a8358

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