mnl has segmentation fault and invalid memory read in `mnl::cb_run`

Summary

The function `mnl::cb_run` is marked as safe but exhibits unsound behavior when processing malformed Netlink message buffers. Passing a crafted byte slice to `mnl::cb_run` can trigger memory violations. The function does not sufficiently validate the input buffer structure before processing, leading to out-of-bounds reads. This vulnerability allows an attacker to cause a Denial of Service (segmentation fault) or potentially read unmapped memory by providing a malformed Netlink message.