linux-kernel - Re: [GIT PULL] hash addresses printed with %p

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Message-ID: <CA+55aFwjhjGZC9U68mo4hnnJXLWYxG3UYoz-=SwNfO-3N-Untg@mail.gmail.com>
Date:   Wed, 29 Nov 2017 13:14:38 -0800
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     "Tobin C. Harding" <me@...in.cc>
Cc:     LKML <linux-kernel@...r.kernel.org>
Subject: Re: [GIT PULL] hash addresses printed with %p

On Wed, Nov 29, 2017 at 1:08 PM, Tobin C. Harding <me@...in.cc> wrote:
>
> If you haven't wasted enough time on this can you tell me what you mean
> by 'completely breaks %pK'?

The whole point of %pK is that it's a "safer" %p that doesn't leak
information if you set kptr_restrict.

With that patch-set, it now leaks _more_ information than %p when
kptr_restrict isn't set, so %pK went from "be more careful than %p" to
"be wildly less careful than %p".

Not because %pK itself changed, but because the semantics of %p did.
The baseline moved, and the "safe" version did not.

                 Linus