linux-kernel - Re: [PATCH V8 0/2] printk: hash addresses printed with %p

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Date:   Fri, 3 Nov 2017 01:04:09 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To:     "Tobin C. Harding" <me@...in.cc>
Cc:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        kernel-hardening@...ts.openwall.com,
        "Jason A. Donenfeld" <Jason@...c4.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>,
        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>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V8 0/2] printk: hash addresses printed with %p

On (11/02/17 21:14), Tobin C. Harding wrote:
[..]
> I can put my email address if there is not a better option.

sounds good.


> > hm... just a huge pile of if's
> > 
> > 	if (is_vmalloc_addr(addr))
> > 		do_hashing(addr);
> > 	else if (__module_address(addr))
> > 		do_hashing(addr);
> > 	else if (is_kernel(addr) || is_kernel_inittext(addr))
> > 	...
> > 
> > but that's going to be really messy and "iffy".
> 
> This is the only suggestion we have so far.
> 

well... one more: check if we can safely dereference it. if so
it's a pointer, probably :)

	if (!probe_kernel_address(addr, p))
		do_hashing(addr);


just an idea.

	-ss