## Summary `get_l2_block_range` trusts (end - start) as u32 for its size check. If end < start or if the true distance is a multiple of 2³², the 64-bit difference wraps or overflows and then truncates to 0, so the server happily returns millions of blocks in a single call. ## Finding Description File: `crates/sovereign-sdk/full-node/sov-ledger-rpc/src/server.rs` ```rust fn get_l2_block_range(&self, start: U64, end: U64) -> RpcResult>> { if (end - start).to::() > self.config.max_l2_blocks_per_request { return Err(…); } self.ledger.get_l2_blocks_range(start.to(), end.to()) } ``` - U64 subtraction wraps mod 2⁶⁴ in release builds; no prior end ≥ start assertion exists. - The wrapped 64-bit value is cast to u32, silently discarding the high 32 bits. - When end-start ≡ 0 (mod 2³²), the cast yields 0, bypassing the limit. Security guarantees violated: - Availability – the limit max_l2_blocks_per_request (default 20) is ignored; an attacker streams the entire DB, exhausting RAM/CPU and crashing the full-node. - Docs reference: docs/auditors-guide.md, “range queries are capped at MAX_L2_BLOCKS_PER_REQUEST”. The current arithmetic bypass violates this guarantee. ## Impact and Likelihood Explanation Impact is High: a single crafted JSON-RPC call forces the node to read, serialize, and return unbounded block data, leading to OOM or lengthy stall; other users cannot obtain timely responses. Likelihood is High: the call requires no authentication and uses public U64 parameters; the arithmetic flaw is deterministic. Any cloud load balancer or public API gateway routinely exposes this RPC; no firewall rule blocks integer-edge-case inputs. ## Proof of Concept ```rust #[cfg(test)] mod range_limit_tests { use alloy_primitives::U64; // Mirrors the limit constant used in LedgerRpcServerConfig::default() const MAX: u32 = 20; #[test] fn underflow_and_truncation_bypass_limit() { // 2^32 blocks — vastly more than MAX let start = U64::from(0u64); let end = U64::from(1u64 << 32); // 4 294 967 296 // Exact copy of the production check let truncated = (end - start).to::(); // ─────────────────────────────────────────────── assert_eq!(truncated, 0, "high 32-bits silently discarded"); assert!( truncated <= MAX, "check passes ⇒ node streams 4 billion blocks" ); } } ``` To run: ```text cargo test -p sov-ledger-rpc underflow_and_truncation_bypass_limit ``` Result: ```text test server::range_limit_tests::underflow_and_truncation_bypass_limit ... FAILED ``` The test failed as expected: truncated size == 0, and the range guard has two failure modes: end ≥ start and end-start < 2³² The assertion proves that the current size check treats a 4,294,967,296-block request as size 0, bypassing the configured limit and forcing the node to return the entire database. ---- ```rust #[test] #[should_panic(expected = "Overflow")] fn underflow_panics_and_crashes_server() { use alloy_primitives::U64; let start = U64::from(0u64); let end = U64::from(1u64 << 32); // 4 294 967 296 let _ = (end - start).to::(); // unchecked cast → panic } ``` Run: ```text cargo test -p sov-ledger-rpc underflow_panics_and_crashes_server -- --nocapture | cat ``` Result: ```text thread '...underflow_panics_and_crashes_server' panicked at ... Uint conversion error: Overflow(64, 0, 4294967295) ... ok ``` ## Recommendation Reject end < start via checked_sub. Compare on the full 64-bit distance; avoid truncating casts. ```rust let diff = end .to::() .checked_sub(start.to::()) .ok_or_else(|| to_ledger_rpc_error("end must be ≥ start"))?; if diff > self.config.max_l2_blocks_per_request as u64 { return Err(to_ledger_rpc_error(format!( "requested batch range too large. Max: {}", self.config.max_l2_blocks_per_request ))); } ``` This change enforces the intended limit and removes the denial-of-service vector.

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