pppoe: reload header pointer after dev_hard_header()

...

CVE-2026-68334

In the Linux kernel, the following vulnerability has been resolved: rxrpc: fix iothread race in rxrpcwakeupiothread rxrpcwakeupiothread checks local-iothread before waking it, but then reloads the pointer for wakeupprocess. local-iothread is cleared with WRITEONCE when the I/O thread exits, so th...