From: Matt Corallo <git@bluematt.me>
Date: Sun, 11 Feb 2024 20:33:35 +0000 (+0000)
Subject: Fix overflowing subtract in vec preallocation
X-Git-Url: http://git.bitcoin.ninja/index.cgi?p=dnssec-prover;a=commitdiff_plain;h=1bc1a6325dce9c48f5610edccb91a38a1abb3084

Fix overflowing subtract in vec preallocation

If a TXT record comes in with zero length data, we'll overflow in
the subtraction and try to allocate much too much data.
---

diff --git a/src/rr.rs b/src/rr.rs
index 9886e3a..c585555 100644
--- a/src/rr.rs
+++ b/src/rr.rs
@@ -218,7 +218,7 @@ impl StaticRecord for Txt {
 		format!("{{\"type\":\"txt\",\"name\":\"{}\",\"contents\":{:?}}}", self.name.0, &self.data[..])
 	}
 	fn read_from_data(name: Name, mut data: &[u8], _wire_packet: &[u8]) -> Result<Self, ()> {
-		let mut parsed_data = Vec::with_capacity(data.len() - 1);
+		let mut parsed_data = Vec::with_capacity(data.len().saturating_sub(1));
 		while !data.is_empty() {
 			let len = read_u8(&mut data)? as usize;
 			if data.len() < len { return Err(()); }