http://bugzilla.suse.com/show_bug.cgi?id=1045340
http://bugzilla.suse.com/show_bug.cgi?id=1045340#c24
--- Comment #24 from Michal Hocko
Created attachment 729855 [details] sk.c
From: Solar Designer
Dear Alexander, probably it is already known, otherwise please share it in oss-security@ I've noticed the problem on Red Hat kernels first, and reported to Red Hat already, but now I've found the same problem on Ubuntu kernels. It does not affect mainline patch "mm: larger stack guard gap, between vmas" but seems distributors have used some other incorrect patch (shared in linux-distros@ ??? )
Description of problem: mmap(MAP_GROUWSDOWN) works incorrectly on Red Hat and Ubuntu kernels with stackguard fix.
We have application that creates stack by using MAP_GROUWSDOWN , provide this area into clone(), where it fails on access to mapped area.
This is a different problem unrelated to this bug. In fact I would argue that we have never supported/implemented MAP_GROUWSDOWN correctly. There is only one stack that can work reliably because we place it above any mmaps or grow mmaps from lower addresses. A larger gap just makes it more obvious. Feel free to open a separate bug for this but I would tend to close it as WONTFIX. -- You are receiving this mail because: You are on the CC list for the bug.