net: fec: remove .ndo_poll_controller to avoid deadlocks

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: net: fec: remove .ndo_poll_controller to avoid deadlocks There is a deadlock issue found in sungem driver, please refer to the commit ac0a230f719b ("eth: sungem: remove .ndo_poll_controller to avoid deadlocks"). The root cause of the issue is that netpoll is in atomic context and disable_irq() is called by .ndo_poll_controller interface of sungem driver, however, disable_irq() might sleep. After analyzing the implementation of fec_poll_controller(), the fec driver should have the same issue. Due to the fec driver uses NAPI for TX completions, the .ndo_poll_controller is unnecessary to be implemented in the fec driver, so fec_poll_controller() can be safely removed.

References

• https://git.kernel.org/stable/c/e2348d8c61d03feece1de4c05f72e6e99f74c650
• https://git.kernel.org/stable/c/d38625f71950e79e254515c5fc585552dad4b33e
• https://git.kernel.org/stable/c/accdd6b912c4219b8e056d1f1ad2e85bc66ee243
• https://git.kernel.org/stable/c/87bcbc9b7e0b43a69d44efa5f32f11e32d08fa6f
• https://git.kernel.org/stable/c/c2e0c58b25a0a0c37ec643255558c5af4450c9f5