Kernel crash via BPF stack-map size overflow

Integer overflow in Linux kernel BPF stack maps on 32-bit systems allows local users to crash the kernel with an oversized map. stack_map_alloc() rounds an attacker-controlled max_entries value to a power of two before checking overflow, so a 32-bit left shift invokes undefined behavior instead of reliably yielding zero. A local low-privileged user must be able to create a BPF stack map; successful triggering interrupts the system without a reported confidentiality or integrity impact.