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webp: Do not panic on overflow if size is maximum #1563

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Oct 2, 2021
Merged

webp: Do not panic on overflow if size is maximum #1563

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28 changes: 26 additions & 2 deletions src/codecs/webp/decoder.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -106,13 +106,17 @@ impl<R: Read> WebPDecoder<R> {
)));
}
_ => {
let mut len = self.r.read_u32::<LittleEndian>()?;
let mut len = u64::from(self.r.read_u32::<LittleEndian>()?);

if len % 2 != 0 {
// RIFF chunks containing an uneven number of bytes append
// an extra 0x00 at the end of the chunk
//
// The addition cannot overflow since we have a u64 that was created from a u32
len += 1;
}
io::copy(&mut self.r.by_ref().take(len as u64), &mut io::sink())?;

io::copy(&mut self.r.by_ref().take(len), &mut io::sink())?;
}
}
}
Expand Down Expand Up @@ -183,3 +187,23 @@ impl<'a, R: 'a + Read> ImageDecoder<'a> for WebPDecoder<R> {
Ok(())
}
}

#[cfg(test)]
mod tests {
use super::*;

#[test]
fn add_with_overflow_size() {
let bytes = vec![0x52, 0x49, 0x46, 0x46, 0xaf, 0x37, 0x80, 0x47, 0x57, 0x45, 0x42, 0x50,
0x6c, 0x64, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xfb, 0x7e, 0x73, 0x00,
0x06, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x05, 0x00, 0x00, 0x00,
0x65, 0x65, 0x65, 0x65, 0x65, 0x65, 0x40, 0xfb, 0xff, 0xff, 0x65, 0x65,
0x65, 0x65, 0x65, 0x65, 0x65, 0x65, 0x65, 0x65, 0x00, 0x00, 0x00, 0x00,
0x62, 0x00, 0x10, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x49, 0x49, 0x54,
0x55, 0x50, 0x4c, 0x54, 0x59, 0x50, 0x45, 0x33, 0x37, 0x44, 0x4d, 0x46];

let data = std::io::Cursor::new(bytes);

let _ = WebPDecoder::new(data);
}
}