CVE-2024-47747: Use After Free

In the Linux kernel, the following vulnerability has been resolved:

net: seeq: Fix use after free vulnerability in ether3 Driver Due to Race Condition

In the ether3_probe function, a timer is initialized with a callback function ether3_ledoff, bound to &prev(dev)->timer. Once the timer is started, there is a risk of a race condition if the module or device is removed, triggering the ether3_remove function to perform cleanup. The sequence of operations that may lead to a UAF bug is as follows:

CPU0 CPU1

| ether3_ledoff ether3_remove | free_netdev(dev); | put_devic | kfree(dev); | | ether3_outw(priv(dev)->regs.config2 |= CFG2_CTRLO, REG_CONFIG2); | // use dev

Fix it by ensuring that the timer is canceled before proceeding with the cleanup in ether3_remove.