xref loop causes qpdf to hang

[hannob]

The attached file will cause an infinite loop in qpdf due to looping xref's.
loop.zip

This is actually an example from a six year old bug in evince, discovered by andreas bogk, see:
https://bugs.launchpad.net/ubuntu/+source/poppler/+bug/825554
https://github.com/andreas23/pdfparser/tree/master/tests

[jberkenbilt]

Thanks. I can reproduce it. Sigh. This one shouldn't be too hard to fix as a special case. I wonder how many other things like this are lurking in qpdf.

[ghost]

This has been assigned CVE-2017-18186