fix: ec_precompiles input padding (#960)

kkrt-labs · Sep 18, 2024 · a4442a6 · a4442a6
1 parent 4b4139b
commit a4442a6
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Showing 2 changed files with 9 additions and 3 deletions.
diff --git a/crates/evm/src/precompiles/ec_add.cairo b/crates/evm/src/precompiles/ec_add.cairo
@@ -12,7 +12,7 @@ use evm::errors::EVMError;
 use evm::precompiles::Precompile;
 use garaga::core::circuit::AddInputResultTrait2;
 use utils::helpers::ToBytes;
-use utils::helpers::load_word;
+use utils::helpers::{load_word, U8SpanExTrait};
 
 
 const BASE_COST: u64 = 150;
@@ -24,9 +24,12 @@ pub impl EcAdd of Precompile {
         0x6.try_into().unwrap()
     }
 
-    fn exec(mut input: Span<u8>) -> Result<(u64, Span<u8>), EVMError> {
+    fn exec(input: Span<u8>) -> Result<(u64, Span<u8>), EVMError> {
         let gas = BASE_COST;
 
+        // Pad the input to 128 bytes to avoid out-of-bounds accesses
+        let mut input = input.pad_right_with_zeroes(128);
+
         let x1_bytes = *(input.multi_pop_front::<32>().unwrap());
         let x1: u256 = load_word(U256_BYTES_LEN, x1_bytes.unbox().span());
 

diff --git a/crates/evm/src/precompiles/ec_mul.cairo b/crates/evm/src/precompiles/ec_mul.cairo
@@ -5,7 +5,7 @@ use evm::errors::EVMError;
 use evm::precompiles::Precompile;
 
 use evm::precompiles::ec_add::{is_on_curve, double_ec_point_unchecked, ec_safe_add};
-use utils::helpers::{load_word, ToBytes};
+use utils::helpers::{load_word, ToBytes, U8SpanExTrait};
 
 // const BN254_ORDER: u256 = 0x30644E72E131A029B85045B68181585D2833E84879B9709143E1F593F0000001;
 
@@ -20,6 +20,9 @@ pub impl EcMul of Precompile {
     fn exec(mut input: Span<u8>) -> Result<(u64, Span<u8>), EVMError> {
         let gas = BASE_COST;
 
+        // Pad the input to 128 bytes to avoid out-of-bounds accesses
+        let mut input = input.pad_right_with_zeroes(96);
+
         let x1_bytes = *(input.multi_pop_front::<32>().unwrap());
         let x1: u256 = load_word(U256_BYTES_LEN, x1_bytes.unbox().span());