Fail secp256k1 if the instruction data looks incorrect (#19300)

sdk/src/feature_set.rs

@@ -199,6 +199,10 @@ pub mod versioned_tx_message_enabled {
     solana_sdk::declare_id!("3KZZ6Ks1885aGBQ45fwRcPXVBCtzUvxhUTkwKMR41Tca");
 }
 
+pub mod libsecp256k1_fail_on_bad_count {
+    solana_sdk::declare_id!("8aXvSuopd1PUj7UhehfXJRg6619RHp8ZvwTyyJHdUYsj");
+}
+
 lazy_static! {
     /// Map of feature identifiers to user-visible description
     pub static ref FEATURE_NAMES: HashMap<Pubkey, &'static str> = [
@@ -243,6 +247,7 @@ lazy_static! {
         (gate_large_block::id(), "validator checks block cost against max limit in realtime, reject if exceeds."),
         (mem_overlap_fix::id(), "memory overlap fix"),
         (versioned_tx_message_enabled::id(), "enable versioned transaction message processing"),
+        (libsecp256k1_fail_on_bad_count::id(), "Fail libsec256k1_verify if count appears wrong")
         /*************** ADD NEW FEATURES HERE ***************/
     ]
     .iter()

sdk/src/secp256k1_instruction.rs

@@ -103,11 +103,18 @@ pub fn verify_eth_addresses(
     data: &[u8],
     instruction_datas: &[&[u8]],
     libsecp256k1_0_5_upgrade_enabled: bool,
+    libsecp256k1_fail_on_bad_count: bool,
 ) -> Result<(), Secp256k1Error> {
     if data.is_empty() {
         return Err(Secp256k1Error::InvalidInstructionDataSize);
     }
     let count = data[0] as usize;
+    if libsecp256k1_fail_on_bad_count && count == 0 && data.len() > 1 {
+        // count is zero but the instruction data indicates that is probably not
+        // correct, fail the instruction to catch probable invalid secp256k1
+        // instruction construction.
+        return Err(Secp256k1Error::InvalidInstructionDataSize);
+    }
     let expected_data_size = count
         .saturating_mul(SIGNATURE_OFFSETS_SERIALIZED_SIZE)
         .saturating_add(1);
@@ -215,7 +222,7 @@ pub mod test {
         let writer = std::io::Cursor::new(&mut instruction_data[1..]);
         bincode::serialize_into(writer, &offsets).unwrap();
 
-        verify_eth_addresses(&instruction_data, &[&[0u8; 100]], false)
+        verify_eth_addresses(&instruction_data, &[&[0u8; 100]], false, true)
     }
 
     #[test]
@@ -230,7 +237,7 @@ pub mod test {
         instruction_data.truncate(instruction_data.len() - 1);
 
         assert_eq!(
-            verify_eth_addresses(&instruction_data, &[&[0u8; 100]], false),
+            verify_eth_addresses(&instruction_data, &[&[0u8; 100]], false, true),
             Err(Secp256k1Error::InvalidInstructionDataSize)
         );
 
@@ -346,4 +353,19 @@ pub mod test {
             Err(Secp256k1Error::InvalidSignature)
         );
     }
+
+    #[test]
+    fn test_count_is_zero_but_sig_data_exists() {
+        solana_logger::setup();
+
+        let mut instruction_data = vec![0u8; DATA_START];
+        let offsets = SecpSignatureOffsets::default();
+        instruction_data[0] = 0;
+        let writer = std::io::Cursor::new(&mut instruction_data[1..]);
+        bincode::serialize_into(writer, &offsets).unwrap();
+        assert_eq!(
+            verify_eth_addresses(&instruction_data, &[&[0u8; 100]], false, true),
+            Err(Secp256k1Error::InvalidInstructionDataSize)
+        );
+    }
 }

sdk/src/transaction/mod.rs

@@ -426,7 +426,11 @@ impl Transaction {
             .collect()
     }
 
-    pub fn verify_precompiles(&self, libsecp256k1_0_5_upgrade_enabled: bool) -> Result<()> {
+    pub fn verify_precompiles(
+        &self,
+        libsecp256k1_0_5_upgrade_enabled: bool,
+        libsecp256k1_fail_on_bad_count: bool,
+    ) -> Result<()> {
         for instruction in &self.message().instructions {
             // The Transaction may not be sanitized at this point
             if instruction.program_id_index as usize >= self.message().account_keys.len() {
@@ -445,6 +449,7 @@ impl Transaction {
                     data,
                     &instruction_datas,
                     libsecp256k1_0_5_upgrade_enabled,
+                    libsecp256k1_fail_on_bad_count,
                 );
                 e.map_err(|_| TransactionError::InvalidAccountIndex)?;
             }

sdk/src/transaction/sanitized.rs

@@ -203,7 +203,11 @@ impl SanitizedTransaction {
     }
 
     /// Verify the encoded secp256k1 signatures in this transaction
-    pub fn verify_precompiles(&self, libsecp256k1_0_5_upgrade_enabled: bool) -> Result<()> {
+    pub fn verify_precompiles(
+        &self,
+        libsecp256k1_0_5_upgrade_enabled: bool,
+        libsecp256k1_fail_on_bad_count: bool,
+    ) -> Result<()> {
         for (program_id, instruction) in self.message.program_instructions_iter() {
             if secp256k1_program::check_id(program_id) {
                 let instruction_datas: Vec<_> = self
@@ -217,6 +221,7 @@ impl SanitizedTransaction {
                     data,
                     &instruction_datas,
                     libsecp256k1_0_5_upgrade_enabled,
+                    libsecp256k1_fail_on_bad_count,
                 );
                 e.map_err(|_| TransactionError::InvalidAccountIndex)?;
             }