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Subject: Re: [PATCH][RESEND] lib/vsprintf: make-printk-non-secret printks all
 addresses as unhashed
To:     Vlastimil Babka <vbabka@suse.cz>, Petr Mladek <pmladek@suse.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        willy@infradead.org, akpm@linux-foundation.org,
        torvalds@linux-foundation.org, roman.fietze@magna.com,
        keescook@chromium.org, john.ogness@linutronix.de,
        akinobu.mita@gmail.com
References: <20210202213633.755469-1-timur@kernel.org>
 <3baace45-38af-a59b-c376-9a4c39a17b2d@suse.cz>
From:   Timur Tabi <timur@kernel.org>
Message-ID: <d6223371-a5e7-28ac-704c-0e3d5b7ea713@kernel.org>
Date:   Fri, 5 Feb 2021 12:25:22 -0600
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On 2/5/21 4:59 AM, Vlastimil Babka wrote:
> Thanks a lot. Should this also affect %pK though? IIUC, there's currently no way
> to achieve non-mangled %pK in all cases, even with the most permissive
> kptr_restrict=1 setting:
> - in IRQ, there's "pK-error" instead
> - in a context of non-CAP_SYSLOG process, nulls are printed

Hmmm..  I thought %pK prints an unhashed pointer when the user is root, 
at least in situations where the user can be known (e.g. during an ioctl 
call).

> Yes, neither should matter if %pK were only used for prints that generate
> content of some kind of /proc file read by a CAP_SYSLOG process, but that
> doesn't seem to be the case and there are %pK used for printing to dmesg too...

I thought about that.  On one hand, people who use %pK probably really 
wanted a hashed pointer printed.  On the other hand, I agree that %pK 
should not be used for dmesg prints.

I get the feeling that some (most?) people who use %pK don't really 
understand how it's supposed to be used.

I can extend make-printk-non-secret to %pK if everyone agrees.