Kernel crash via pre-rounding BPF bucket overflow

Integer overflow in the Linux kernel BPF hashtable on 32-bit systems allows local users to crash the kernel through a crafted map. The bucket count is rounded before the overflow guard, so a 32-bit unsigned-long shift invokes undefined behavior instead of reliably producing the zero value that the guard expects. The path requires local low-privileged access to create a large BPF hash map; Siemens rates the product-specific consequence as an availability loss.