bgpd: fix integer overflow in maximum prefix threshold check

[guoguojia2021]

Cast pmax to uint64_t before the multiplication so the product is computed in 64-bit arithmetic, correctly handling prefix limits up to the uint32_t maximum (~4 billion) with any threshold percentage.

[greptile-apps]

Greptile Summary

This PR fixes an integer overflow in the BGP maximum-prefix threshold check inside bgp_maximum_prefix_overflow(). The multiplication peer->pmax[afi][safi] * peer->pmax_threshold[afi][safi] was performed in 32-bit arithmetic (both uint32_t and uint8_t), which could overflow when pmax is large; casting pmax to uint64_t forces the product into 64-bit arithmetic before dividing by 100.

• The cast is applied only to the threshold warning path (line 5367); the hard-limit check on line 5306 compares pcount > pmax directly and does not multiply, so it is not affected.
• pcount (uint32_t) is safely promoted to uint64_t for the comparison, and the right-hand side after dividing by 100 can never exceed UINT32_MAX since pmax is uint32_t and pmax_threshold is at most 100.

Confidence Score: 5/5

The change is a single targeted cast that corrects arithmetic promotion in the threshold warning path and has no effect on the hard-limit or session-teardown paths.

The fix is a single-line cast from uint32_t to uint64_t before a multiplication. The hard-limit comparison on line 5306 is unaffected. The pcount operand on the left side of the threshold comparison is uint32_t and is safely widened for the comparison. The maximum product after the cast (UINT32_MAX × 100) is well within uint64_t range, and the result after dividing by 100 fits back within uint32_t range, so the comparison semantics are preserved in all non-overflow cases and corrected in overflow cases.

No files require special attention.

Important Files Changed

Filename	Overview
bgpd/bgp_route.c	One-line cast fix for integer overflow in threshold comparison; change is minimal, correct, and does not affect surrounding logic.

_{Reviews (1): Last reviewed commit: "bgpd: fix integer overflow in maximum pr..." | Re-trigger Greptile}

[riw777]

please fix lint errors ... otherwise good