Inflation algorithm used for decoding can go into infinite loop

[tommy2is]

Issue: Application hangs while attempting to decode image from the internet.

Expected: Should be able to handle any input, throws error if input is invalid

Details: My application would hang on line 237 - in the decoded loop below

             while (!0) {
                var T = v[e(N, d) & X];
                d += T & 15;
                var p = T >>> 4;
                if (p >>> 8 == 0) {
                    W[w++] = p;
                } else if (p == 256) {
                    break;
                } else {
                  ......
                }
            }

I'm not sure what the above does, other than the fact that it's part of zlib. However, X would be 0, d would change, but T is 3 and p is always 0, and it enters an infinite loop.

[photopea]

Hi, sorry, we can guarantee a correct functinality only on valid PNG images. If your image is invalid, we can not guarantee any meaningful behaviour :(

Maybe you can make your fork of UPNG.js and replace our inflater with pako.js , which can throw errors when there are errors.

[photopea]

Or is it a valid PNG? Could you share it with us?