Messages in this thread | | | From | "Roberts, William C" <> | Subject | RE: [PATCH V11 4/5] vsprintf: add printk specifier %px | Date | Wed, 29 Nov 2017 22:36:28 +0000 |
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> -----Original Message----- > From: keescook@google.com [mailto:keescook@google.com] On Behalf Of Kees > Cook > Sent: Wednesday, November 29, 2017 2:28 PM > To: David Laight <David.Laight@aculab.com> > Cc: Linus Torvalds <torvalds@linux-foundation.org>; Tobin C. Harding > <me@tobin.cc>; kernel-hardening@lists.openwall.com; Jason A. Donenfeld > <Jason@zx2c4.com>; Theodore Ts'o <tytso@mit.edu>; Paolo Bonzini > <pbonzini@redhat.com>; Tycho Andersen <tycho@tycho.ws>; Roberts, William C > <william.c.roberts@intel.com>; Tejun Heo <tj@kernel.org>; Jordan Glover > <Golden_Miller83@protonmail.ch>; Greg KH <gregkh@linuxfoundation.org>; > Petr Mladek <pmladek@suse.com>; Joe Perches <joe@perches.com>; Ian > Campbell <ijc@hellion.org.uk>; Sergey Senozhatsky > <sergey.senozhatsky@gmail.com>; Catalin Marinas <catalin.marinas@arm.com>; > Will Deacon <wilal.deacon@arm.com>; Steven Rostedt <rostedt@goodmis.org>; > Chris Fries <cfries@google.com>; Dave Weinstein <olorin@google.com>; Daniel > Micay <danielmicay@gmail.com>; Djalal Harouni <tixxdz@gmail.com>; Radim > Krcmár <rkrcmar@redhat.com>; Linux Kernel Mailing List <linux- > kernel@vger.kernel.org>; Network Development <netdev@vger.kernel.org>; > David Miller <davem@davemloft.net>; Stephen Rothwell > <sfr@canb.auug.org.au>; Andrey Ryabinin <aryabinin@virtuozzo.com>; > Alexander Potapenko <glider@google.com>; Dmitry Vyukov > <dvyukov@google.com>; Andrew Morton <akpm@linux-foundation.org> > Subject: Re: [PATCH V11 4/5] vsprintf: add printk specifier %px > > On Wed, Nov 29, 2017 at 2:07 AM, David Laight <David.Laight@aculab.com> > wrote: > > From: Linus Torvalds > >> Sent: 29 November 2017 02:29 > >> > >> On Tue, Nov 28, 2017 at 6:05 PM, Tobin C. Harding <me@tobin.cc> wrote: > >> > > >> > Let's add specifier %px as a > >> > clear, opt-in, way to print a pointer and maintain some level of > >> > isolation from all the other hex integer output within the Kernel. > >> > >> Yes, I like this model. It's easy and it's obvious ("'x' for hex"), > >> and it gives people a good way to say "yes, I really want the actual > >> address as hex" for if/when the hashed pointer doesn't work for some > >> reason. > > > > Remind me to change every %p to %px on kernels that support it. > > > > Although the absolute values of pointers may not be useful, knowing > > that two pointer differ by a small amount is useful. > > It is also useful to know whether pointers are to stack, code, static > > data or heap. > > > > This change to %p is going to make debugging a nightmare. > > In the future, maybe we could have a knob: unhashed, hashed (default), or > zeroed.
Isn't that just kptr_restrict and get us right back to the simpler patches I proposed?
> > -Kees > > -- > Kees Cook > Pixel Security
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