linux-kernel - Re: [PATCH V11 3/5] printk: hash addresses printed with %p

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Message-ID: <CA+55aFy4qnm3m5QupLMcp-8k0yz6E_-ug6rE-1aerpEQObYcLw@mail.gmail.com>
Date:   Wed, 6 Dec 2017 15:28:22 -0800
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Kees Cook <keescook@...omium.org>
Cc:     David Laight <David.Laight@...lab.com>,
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Subject: Re: [PATCH V11 3/5] printk: hash addresses printed with %p

On Wed, Dec 6, 2017 at 3:21 PM, Kees Cook <keescook@...omium.org> wrote:
> On Wed, Dec 6, 2017 at 2:31 AM, David Laight <David.Laight@...lab.com> wrote:
>>
>> I can also image issues where you want to know whether 2 pointers point
>> into the same structure (like an skb).
>
> This is already retained due to the hashing. i.e. the same pointer
> value will produce the same hash value, so that kind of direct
> comparison still works.

DavidL isn't talking about the _same_ pointer, he's talking about it
being offset from the same base.

But realistically, I don't think we ever hash things like that anyway.

Things like that do show up in register dumps etc during oopses, but
those aren't hashed.

            Linus