Panic when reading jpeg

[frewsxcv]

extern crate image;

use std::io::Cursor;
use image::ImageDecoder;

fn main() {
    let input = b"\xff\xda\x30\x30\x30\x30\x30".to_vec();
    let c = Cursor::new(input);
    let _ = image::jpeg::JPEGDecoder::new(c).read_image();
}

coreyf@frewbook-pro /t/tmp (master)> cargo run
   Compiling tmp v0.1.0 (file:///private/tmp/tmp)
     Running `target/debug/tmp`
thread '<main>' panicked at 'called `Option::unwrap()` on a `None` value', ../src/libcore/option.rs:365
Process didn't exit successfully: `target/debug/tmp` (exit code: 101)

found using afl.rs

[mbrubeck]

Here's a backtrace:

   9:     0x557b484c749a - option::_<impl>::unwrap::unwrap::h15182871008768225708
                        at ../src/libcore/macros.rs:20
  10:     0x557b484c6f13 - jpeg::decoder::_<impl>::read_scan_header::read_scan_header::h6101705012787530129
                        at src/jpeg/decoder.rs:393
  11:     0x557b484b6651 - jpeg::decoder::_<impl>::read_metadata::read_metadata::h10468609051219687808
                        at src/jpeg/decoder.rs:280
  12:     0x557b484b5a38 - jpeg::decoder::_<impl>::read_image::read_image::h9136914022092451839
                        at src/jpeg/decoder.rs:600

The line doing the unwrapping is:

            let c = self.components.get_mut(&(id as usize)).unwrap();

[nwin]

Yes, the JPEG is invalid, still shouldn’t crash of course.