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 size of the `rule_buf` array is determined by multiplying `info.rule_cnt` by `sizeof(u32)` without first checking if the resulting size is valid. This can lead to an integer overflow if `info.rule_cnt` is very large, which can result in allocating a buffer that is too small to hold the rule data. This can lead to an out-of-bounds write vulnerability when the `ops->get_rxnfc` function attempts to write to the `rule_buf` array, which is CWE-787.