lkml.org 
[lkml]   [2017]   [Nov]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH V11 0/5] hash addresses printed with %p
    On Wed, 29 Nov 2017 13:05:00 +1100 "Tobin C. Harding" <me@tobin.cc> wrote:

    > Currently there exist approximately 14 000 places in the Kernel where
    > addresses are being printed using an unadorned %p. This potentially
    > leaks sensitive information regarding the Kernel layout in memory. Many
    > of these calls are stale, instead of fixing every call lets hash the
    > address by default before printing. This will of course break some
    > users, forcing code printing needed addresses to be updated. We can add
    > a printk specifier for this purpose (%px) to give developers a clear
    > upgrade path for breakages caused by applying this patch set.
    >
    > The added advantage of hashing %p is that security is now opt-out, if
    > you _really_ want the address you have to work a little harder and use
    > %px.
    >
    > The idea for creating the printk specifier %px to print the actual
    > address was suggested by Kees Cook (see below for email threads by
    > subject).

    Maybe I'm being thick, but... if we're rendering these addresses
    unusable by hashing them, why not just print something like
    "<obscured>" in their place? That loses the uniqueness thing but I
    wonder how valuable that is in practice?


    \
     
     \ /
      Last update: 2017-11-30 00:21    [W:3.086 / U:0.028 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site