Phil Sutter

A possible ABBA deadlock vulnerability has been identified in the Linux kernel, specifically in the netfilter IDLETIMER module. This issue occurs when the deletion of the last rule referencing a given idletimer happens simultaneously with a read of its file in sysfs, resulting in a possible circular locking dependency. A simple reproducer for this issue is provided, demonstrating how the deadlock can occur. The vulnerability is resolved by freeing the `list mutex` immediately after deleting the element from the list and then continuing with the teardown.

A race condition in the Linux kernel's netfilter: ipset module can lead to a kernel crash. This occurs when user space unloads the ip set.ko module while it is requesting a set type backend module. The issue can be provoked by inserting a delay after the nfnl unlock() call.