fix: prevent parse_bytecode_pattern error on large OP_PUSHDATA_4 lengths

Author: bitjson

images/hasura/hasura-data/migrations/default/1676794104752_parse_bytecode_pattern/down.sql

@@ -0,0 +1 @@
+-- Could not auto-generate a down migration.

images/hasura/hasura-data/migrations/default/1676794104752_parse_bytecode_pattern/up.sql

@@ -0,0 +1,54 @@
+-- This implementation resolves an error when parsing large OP_PUSHDATA_4 pushes
+CREATE OR REPLACE FUNCTION parse_bytecode_pattern(bytecode bytea) RETURNS bytea
+  LANGUAGE plpgsql IMMUTABLE
+AS $$
+DECLARE
+  pattern bytea := '\x'::bytea;
+  selected_byte integer;
+  scratch bytea;
+  i integer := 0;
+  bytecode_length integer := octet_length(bytecode);
+BEGIN
+  WHILE i < bytecode_length LOOP
+    selected_byte := get_byte(bytecode, i);
+    pattern := pattern || substring(bytecode from (i + 1) for 1);
+    IF selected_byte > 78 OR selected_byte = 0 THEN
+        -- OP_0 (0) and all opcodes after OP_PUSHDATA_4 (78) are single-byte instructions
+      i := i + 1;
+    ELSIF selected_byte > 0 AND selected_byte <= 75 THEN
+      -- OP_PUSHBYTES_1 (1) through OP_PUSHBYTES_75 (75) directly indicate the length of pushed data
+      i := i + 1 + selected_byte;
+    ELSIF selected_byte = 76 THEN
+      IF bytecode_length - i < 2 THEN
+        -- malformed, return immediately
+        RETURN pattern;
+      END IF;
+      -- OP_PUSHDATA_1 reads one length-byte
+      i := i + 2 + get_byte(bytecode, (i + 1));
+    ELSIF selected_byte = 77 THEN
+      IF bytecode_length - i < 3 THEN
+        -- malformed, return immediately
+        RETURN pattern;
+      END IF;
+      -- OP_PUSHDATA_2 reads two length-bytes
+      scratch := substring(bytecode from (i + 2) for 2);
+      -- parse scratch as unsigned, two byte, little-endian number:
+      i := i + 3 + ((get_byte(scratch, 1) << 8) | get_byte(scratch, 0));
+    ELSIF selected_byte = 78 THEN
+      IF bytecode_length - i < 5 THEN
+        -- malformed, return immediately
+        RETURN pattern;
+      END IF;
+      -- OP_PUSHDATA_4 reads four length-bytes
+      scratch := substring(bytecode from (i + 2) for 4);
+      IF get_byte(scratch, 3) << 24 < 0 THEN
+        -- push length exceeds maximum signed int (>2GB), return immediately
+        RETURN pattern;
+      END IF;
+      -- parse scratch as unsigned, four byte, little-endian number:
+      i := i + 5 + ((get_byte(scratch, 3) << 24) | (get_byte(scratch, 2) << 16) | (get_byte(scratch, 1) << 8) | get_byte(scratch, 0));
+    END IF;
+  END LOOP;
+    RETURN pattern;
+END;
+$$;

src/e2e/e2e.spec.ts

@@ -62,6 +62,7 @@ const migration = (path: string) =>
 const dbUpMigrationPaths = [
   migration('default/1616195337538_init/up.sql'),
   migration('default/1673124945608_tokens/up.sql'),
+  migration('default/1676794104752_parse_bytecode_pattern/up.sql'),
 ];
 
 const chaingraphInternalApiPort = '3201';