Messages in this thread | | | Subject | Re: [kernel-hardening] [RFC 3/6] lib: vsprintf: physical address kernel pointer filtering options | From | Ian Campbell <> | Date | Sat, 06 May 2017 11:48:36 +0100 |
| |
On Fri, 2017-05-05 at 21:07 -0700, Greg KH wrote: > From: Dave Weinstein <olorin@google.com> > > Add the kptr_restrict setting of 4 which results in %pa and > %p[rR] values being replaced by zeros.
Given that '%pa' is: * - 'a[pd]' For address types [p] phys_addr_t, [d] dma_addr_t and derivatives * (default assumed to be phys_addr_t, passed by reference)
what is the thread model which hiding physical addresses from attackers protects against? I can see why virtual addresses would be obviously dangerous but physical addresses seem less obvious and I didn't see it spelled out in any of the commit messages or added comments in the thread.
I think a comment somewhere would be useful for people who are trying to decide if they should use %pa vs %paP etc.
Ian.
| |