linux-kernel - Re: [PATCH v7] printk: hash addresses printed with %p

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Date:   Tue, 24 Oct 2017 13:25:52 +0200
From:   "Jason A. Donenfeld" <Jason@...c4.com>
To:     "Tobin C. Harding" <me@...in.cc>
Cc:     kernel-hardening@...ts.openwall.com,
        "Theodore Ts'o" <tytso@....edu>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Kees Cook <keescook@...omium.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Tycho Andersen <tycho@...ker.com>,
        "Roberts, William C" <william.c.roberts@...el.com>,
        Tejun Heo <tj@...nel.org>,
        Jordan Glover <Golden_Miller83@...tonmail.ch>,
        Greg KH <gregkh@...uxfoundation.org>,
        Petr Mladek <pmladek@...e.com>, Joe Perches <joe@...ches.com>,
        Ian Campbell <ijc@...lion.org.uk>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <wilal.deacon@....com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Chris Fries <cfries@...gle.com>,
        Dave Weinstein <olorin@...gle.com>,
        Daniel Micay <danielmicay@...il.com>,
        Djalal Harouni <tixxdz@...il.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v7] printk: hash addresses printed with %p

On Tue, Oct 24, 2017 at 2:31 AM, Tobin C. Harding <me@...in.cc> wrote:
> On Tue, Oct 24, 2017 at 01:00:03AM +0200, Jason A. Donenfeld wrote:
>> Provided you've tested this and the static_key guard stuff actually
>> works as intended,
>
> I tested by inserting a simple module that calls printf() with a bunch of
> different specifiers. So it's tested but not stress tested. Some stress testing
> might be nice, no ideas how to go about that though.

By the way, it occurred to me one thing you might want to verify
closely is whether or not that callback block executes from process
context and whether or not the static_key stuff sleeps. If both,
there's a problem.