While everyone's going wild hndl->dump'ing with CVE-2013-1763, there's apparently been another silent security fix with 5f00110f7273f9ff04ac69a5f85bb535a4fd0987 [1]: tmpfs: fix use-after-free of mempolicy object The tmpfs remount logic preserves filesystem mempolicy if the mpol=M option is not specified in the remount request. A new policy can be specified if mpol=M is given. Before this patch remounting an mpol bound tmpfs without specifying mpol= mount option in the remount request would set the filesystem's mempolicy object to a freed mempolicy object. How far back does this issue go? I see it in both 2.6.36 and 3.3. I did not look back further. The commit message goes on with details on how to trigger it. Note that as of 5eaf563e53294d6696e651466697eb9d491f3946 [2], you can now mount filesystems as an unprivileged user after a call to unshare(CLONE_NEWUSER | CLONE_NEWNS), or a similar clone(2) call. This means all those random random filesystem bugs you have laying around in the junk bin are now quite useful. ++tricks; Cheers, Jason [1] http://git.zx2c4.com/linux/commit/?id=5f00110f7273f9ff04ac69a5f85bb535a4fd0987 [2] http://git.zx2c4.com/linux/commit/?id=5eaf563e53294d6696e651466697eb9d491f3946 -- Jason A. Donenfeld