firmware: arm_ffa: Fix memory leak by freeing notifier callback node

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: firmware: arm_ffa: Fix memory leak by freeing notifier callback node Commit e0573444edbf ("firmware: arm_ffa: Add interfaces to request notification callbacks") adds support for notifier callbacks by allocating and inserting a callback node into a hashtable during registration of notifiers. However, during unregistration, the code only removes the node from the hashtable without freeing the associated memory, resulting in a memory leak. Resolve the memory leak issue by ensuring the allocated notifier callback node is properly freed after it is removed from the hashtable entry.

References

• https://git.kernel.org/stable/c/076fa20b4f5737c34921dbb152f9efceaee571b2
• https://git.kernel.org/stable/c/938827c440564b2cf2f9b804d1fe81ce8267eded
• https://git.kernel.org/stable/c/a833d31ad867103ba72a0b73f3606f4ab8601719