From f2e89140ed26a26886d4dda26a9ab7c55f85a7b8 Mon Sep 17 00:00:00 2001
From: Kornel <kornel@geekhood.net>
Date: Wed, 24 Feb 2021 20:48:30 +0000
Subject: [PATCH] Prevent panics in parse_ihdr_header (#392)

---
 src/headers.rs | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/headers.rs b/src/headers.rs
index 7a328e7b..049ec00c 100644
--- a/src/headers.rs
+++ b/src/headers.rs
@@ -140,6 +140,8 @@ pub fn parse_next_header<'a>(
 }
 
 pub fn parse_ihdr_header(byte_data: &[u8]) -> PngResult<IhdrData> {
+    // This eliminates bounds checks for the rest of the function
+    let interlaced = byte_data.get(12).copied().ok_or(PngError::TruncatedData)?;
     let mut rdr = Cursor::new(&byte_data[0..8]);
     Ok(IhdrData {
         color_type: match byte_data[9] {
@@ -162,6 +164,6 @@ pub fn parse_ihdr_header(byte_data: &[u8]) -> PngResult<IhdrData> {
         height: rdr.read_u32::<BigEndian>().unwrap(),
         compression: byte_data[10],
         filter: byte_data[11],
-        interlaced: byte_data[12],
+        interlaced,
     })
 }