On Mon, Dec 04, 2017 at 06:20:06AM +0100, Linus Lüssing wrote: > On Mon, Dec 04, 2017 at 05:53:35AM +0100, Linus Lüssing wrote: > > And so, no I do not have this patch. I looked at it now, but it > > does not seem to have any relation with .matchinfo, does it? > > Relation between .usersize and .checkentry I ment, not > .usersize and .matchinfo.
In your patch, info->prev comes set to a value from userspace, right? commit 324318f0248c31be8a08984146e7e4dd7cdd091d Author: Willem de Bruijn <will...@google.com> Date: Tue May 9 16:17:37 2017 -0400 netfilter: xtables: zero padding in data_to_user Since that patch above, the data area is zero'ed before dumped to userspace, so we would get a null info->prev, hence defeating the trick your patch relies on. Am I missing anything?