From: Valentine Wallace <vwallace@protonmail.com>
Date: Fri, 5 Aug 2022 17:15:57 +0000 (-0400)
Subject: Fix fuzzer-found underflow
X-Git-Tag: v0.0.111~35^2~1
X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=commitdiff_plain;h=81b7b03d4ff7424e61b073b81cf4edf627c8694b;p=rust-lightning

Fix fuzzer-found underflow
---

diff --git a/lightning/src/onion_message/packet.rs b/lightning/src/onion_message/packet.rs
index a3414d844..d4ba28c84 100644
--- a/lightning/src/onion_message/packet.rs
+++ b/lightning/src/onion_message/packet.rs
@@ -69,7 +69,7 @@ impl LengthReadable for Packet {
 		let public_key = Readable::read(r)?;
 
 		let mut hop_data = Vec::new();
-		let hop_data_len = r.total_bytes() as usize - 66; // 1 (version) + 33 (pubkey) + 32 (HMAC) = 66
+		let hop_data_len = r.total_bytes().saturating_sub(66) as usize; // 1 (version) + 33 (pubkey) + 32 (HMAC) = 66
 		let mut read_idx = 0;
 		while read_idx < hop_data_len {
 			let mut read_buffer = [0; READ_BUFFER_SIZE];