Re: [PATCH 3/6] x86/dumpstack: make printk_stack_address() more generally useful

[Kees Cook]

On Thu, Aug 25, 2016 at 5:23 PM, Linus Torvalds
<torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
> On Aug 25, 2016 2:08 PM, "Josh Poimboeuf" <jpoimboe@xxxxxxxxxx> wrote:
>>
>> Ah, the plot thickens.  I didn't know about 'dmesg_restrict'.  So I
>> guess we don't have to restrict the stack dump addresses after all,
>> since the entire dmesg buffer is protected by syslog()?
>
> No.
>
> Guys, the whole dmesg_restrict thing is a joke. You can't restrict access to
> system messages in general. It's just a stupid idea.

I'm not advocating that it's a globally useful protection, I was just
trying to point out that so much stuff is already exposed in the
system log that it's likely not a great use of time to think about
censoring things there right now. Obviously if it both improves
debuggability _and_ removes raw addresses from the log, I'm all for
it. :)

-Kees

-- 
Kees Cook
Nexus Security