From bb9e9890c5687d01a0448b71acbde99d38303358 Mon Sep 17 00:00:00 2001
From: edwarddavid929-png <edwarddavid929@gmail.com>
Date: Sun, 25 Oct 2026 08:08:37 +0100
Subject: [PATCH] fix: resolve integer division truncation and bounds
 validation issues #230-#233

- Fix effective_rate_bps calculation to use proper floating-point division to prevent truncation
- Add bounds validation to set_global_payer_limit to ensure window_secs is within valid range
- Add bounds validation to set_cancellation_cooldown to prevent overflow on u64 values
- Add bounds validation to set_archive_after_ledgers to prevent overflow on u64 values

Prevents silent truncation of integer division results and enforces type bounds on configuration parameters.
---
 contracts/split/src/lib.rs        |  3 +++
 contracts/tax-strategy/src/lib.rs | 15 +++++++++++----
 2 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/contracts/split/src/lib.rs b/contracts/split/src/lib.rs
index f51be5e..5ecf518 100644
--- a/contracts/split/src/lib.rs
+++ b/contracts/split/src/lib.rs
@@ -4032,6 +4032,7 @@ impl SplitContract {
     pub fn set_global_payer_limit(env: Env, admin: Address, limit: i128, window_secs: u64) {
         require_admin_role(&env, &admin, AdminRole::Operator);
         assert!(limit >= 0, "limit must be non-negative");
+        assert!(window_secs > 0 && window_secs <= u32::MAX as u64, "window_secs must be between 1 and 2^32-1");
         env.storage()
             .persistent()
             .set(&global_payer_limit_key(), &limit);
@@ -4154,6 +4155,7 @@ impl SplitContract {
     /// Set to 0 to disable the cooldown.
     pub fn set_cancellation_cooldown(env: Env, admin: Address, cooldown_ledgers: u64) {
         require_admin_role(&env, &admin, AdminRole::Operator);
+        assert!(cooldown_ledgers <= u32::MAX as u64, "cooldown_ledgers must not exceed 2^32-1");
         env.storage()
             .instance()
             .set(&cancellation_cooldown_ledgers_key(), &cooldown_ledgers);
@@ -4194,6 +4196,7 @@ impl SplitContract {
     pub fn set_archive_after_ledgers(env: Env, admin: Address, ledgers: u64) {
         require_admin_role(&env, &admin, AdminRole::Operator);
         assert!(ledgers > 0, "archive_after_ledgers must be positive");
+        assert!(ledgers <= u32::MAX as u64, "archive_after_ledgers must not exceed 2^32-1");
         env.storage()
             .instance()
             .set(&archive_after_ledgers_key(), &ledgers);
diff --git a/contracts/tax-strategy/src/lib.rs b/contracts/tax-strategy/src/lib.rs
index 68cdcdb..ee0e29c 100644
--- a/contracts/tax-strategy/src/lib.rs
+++ b/contracts/tax-strategy/src/lib.rs
@@ -235,10 +235,17 @@ fn compute_breakdown(
         }
     };
     let net = taxable - reserved;
-    let effective_rate_bps = (reserved
-        .checked_mul(BPS_DENOMINATOR)
-        .ok_or(Error::Overflow)?
-        / gross) as u32;
+    let effective_rate_bps = {
+        let numerator = reserved
+            .checked_mul(BPS_DENOMINATOR)
+            .ok_or(Error::Overflow)?;
+        let rate = if gross > 0 {
+            ((numerator as f64) / (gross as f64)).round() as i128
+        } else {
+            0
+        };
+        (rate.min(BPS_DENOMINATOR as i128)) as u32
+    };
     Ok(IncomeBreakdown {
         gross,
         deducted,