Root Cause Analysis: Looking at the given vulnerable code line and its context, the CWE-787 (out-of-bounds write) vulnerability exists in the code because the variable `info.rule_cnt` is used to allocate memory for the `rule_buf` array without checking if `info.rule_cnt` is 0. If `info.rule_cnt` is 0, then allocating memory for `rule_buf` with `info.rule_cnt * sizeof(u32)` will result in an out-of-bounds write vulnerability, which is CWE-787.