audit/6: short circuit scaling if mpsPerPriorityFeeWei is 0 (#263)

* short circuit scaling if mpsPerPriorityFeeWei is 0 * add test for short circuit case
Uniswap · Aug 2, 2024 · 9fefbea · 9fefbea
1 parent d4b7da8
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Showing 14 changed files with 32 additions and 15 deletions.
diff --git a/.forge-snapshots/Base-PriorityOrderReactor-BaseExecuteSingleWithFee.snap b/.forge-snapshots/Base-PriorityOrderReactor-BaseExecuteSingleWithFee.snap
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diff --git a/.forge-snapshots/Base-PriorityOrderReactor-ExecuteBatch.snap b/.forge-snapshots/Base-PriorityOrderReactor-ExecuteBatch.snap
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diff --git a/.forge-snapshots/Base-PriorityOrderReactor-ExecuteBatchMultipleOutputs.snap b/.forge-snapshots/Base-PriorityOrderReactor-ExecuteBatchMultipleOutputs.snap
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diff --git a/.forge-snapshots/Base-PriorityOrderReactor-ExecuteBatchMultipleOutputsDifferentTokens.snap b/.forge-snapshots/Base-PriorityOrderReactor-ExecuteBatchMultipleOutputsDifferentTokens.snap
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diff --git a/.forge-snapshots/Base-PriorityOrderReactor-ExecuteBatchNativeOutput.snap b/.forge-snapshots/Base-PriorityOrderReactor-ExecuteBatchNativeOutput.snap
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diff --git a/.forge-snapshots/Base-PriorityOrderReactor-ExecuteSingle.snap b/.forge-snapshots/Base-PriorityOrderReactor-ExecuteSingle.snap
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diff --git a/.forge-snapshots/Base-PriorityOrderReactor-ExecuteSingleNativeOutput.snap b/.forge-snapshots/Base-PriorityOrderReactor-ExecuteSingleNativeOutput.snap
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diff --git a/.forge-snapshots/Base-PriorityOrderReactor-ExecuteSingleValidation.snap b/.forge-snapshots/Base-PriorityOrderReactor-ExecuteSingleValidation.snap
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diff --git a/.forge-snapshots/Base-PriorityOrderReactor-InputPriorityFee.snap b/.forge-snapshots/Base-PriorityOrderReactor-InputPriorityFee.snap
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diff --git a/.forge-snapshots/Base-PriorityOrderReactor-OutputPriorityFee.snap b/.forge-snapshots/Base-PriorityOrderReactor-OutputPriorityFee.snap
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diff --git a/.forge-snapshots/Base-PriorityOrderReactor-OutputPriorityFeeAndBaselinePriorityFee.snap b/.forge-snapshots/Base-PriorityOrderReactor-OutputPriorityFeeAndBaselinePriorityFee.snap
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diff --git a/.forge-snapshots/Base-PriorityOrderReactor-OverrideAuctionTargetBlock.snap b/.forge-snapshots/Base-PriorityOrderReactor-OverrideAuctionTargetBlock.snap
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diff --git a/src/lib/PriorityFeeLib.sol b/src/lib/PriorityFeeLib.sol
@@ -27,7 +27,7 @@ library PriorityFeeLib {
         unchecked {
             return InputToken({
                 token: input.token,
-                amount: input.amount.mulDivDown((MPS - scalingFactor), MPS),
+                amount: scalingFactor == 0 ? input.amount : input.amount.mulDivDown((MPS - scalingFactor), MPS),
                 maxAmount: input.amount
             });
         }
@@ -41,7 +41,9 @@ library PriorityFeeLib {
     function scale(PriorityOutput memory output, uint256 priorityFee) internal pure returns (OutputToken memory) {
         return OutputToken({
             token: output.token,
-            amount: output.amount.mulDivUp((MPS + (priorityFee * output.mpsPerPriorityFeeWei)), MPS),
+            amount: output.mpsPerPriorityFeeWei == 0
+                ? output.amount
+                : output.amount.mulDivUp((MPS + (priorityFee * output.mpsPerPriorityFeeWei)), MPS),
             recipient: output.recipient
         });
     }

diff --git a/test/lib/PriorityFeeLib.t.sol b/test/lib/PriorityFeeLib.t.sol
@@ -103,12 +103,27 @@ contract PriorityFeeLibTest is Test {
         uint256 largeAmount = type(uint256).max / MPS + 1;
 
         PriorityOutput memory output =
-            PriorityOutput({token: address(0), amount: largeAmount, mpsPerPriorityFeeWei: 0, recipient: address(0)});
+            PriorityOutput({token: address(0), amount: largeAmount, mpsPerPriorityFeeWei: 1, recipient: address(0)});
 
         vm.expectRevert();
         PriorityFeeLib.scale(output, tx.gasprice);
     }
 
+    /// @notice an otherwise reverting large amount should be short circuited if the mpsPerPriorityFeeWei is 0
+    function testScaleLargeOutputShortCircuit() public {
+        uint256 priorityFee = 0;
+        vm.txGasPrice(priorityFee);
+        assertEq(tx.gasprice, priorityFee);
+
+        uint256 largeAmount = type(uint256).max / MPS + 1;
+
+        PriorityOutput memory output =
+            PriorityOutput({token: address(0), amount: largeAmount, mpsPerPriorityFeeWei: 0, recipient: address(0)});
+
+        OutputToken memory scaledOutput = PriorityFeeLib.scale(output, tx.gasprice);
+        assertEq(scaledOutput.amount, output.amount);
+    }
+
     function testScaleOutputPriorityFee_fuzz(uint256 priorityFee, uint256 mpsPerPriorityFeeWei) public {
         // the amount of MPS to scale the output by
         uint256 scalingFactor = MPS;