Re: [PATCH 0/2] introduce DUMP_PREFIX_UNHASHED for hex dumps

From: Matthew Wilcox
Date: Mon Jan 18 2021 - 20:48:52 EST

On Tue, Jan 19, 2021 at 09:53:01AM +0900, Sergey Senozhatsky wrote:
> On (21/01/18 13:03), Timur Tabi wrote:
> > On 1/18/21 12:26 PM, Matthew Wilcox wrote:
> > > Don't make it easy. And don't make it look like they're doing
> > > something innocent. DUMP_PREFIX_SECURITY_HOLE would be OK
> > > by me. DUMP_PREFIX_LEAK_INFORMATION would work fine too.
> > > DUMP_PREFIX_MAKE_ATTACKERS_LIFE_EASY might be a bit too far.
> >
> > It's already extremely easy to replace %p with %px in your own printks, so I
> > don't really understand your argument.
> I like the idea of a more radical name, e.g. DUMP_PREFIX_RAW_POINTERS or
> something similar.
> > Seriously, this patch should not be so contentious. If you want hashed
> > addresses, then nothing changes. If you need unhashed addresses while
> > debugging, then use DUMP_PREFIX_UNHASHED. Just like you can use %px in
> > printk. I never use %p in my printks, but then I never submit code upstream
> > that prints addresses, hashed or unhashed.

I'm glad to hear you never make mistakes. I make lots of mistakes, so
I prefer them to be big, loud and obvious so they're easy for people
to spot.

> So maybe DUMP_PREFIX_UNHASHED can do the unhashed dump only when
> CONFIG_DEBUG_KERNEL=y and fallback to DUMP_PREFIX_ADDRESS otherwise?

Distros enable CONFIG_DEBUG_KERNEL. If you want to add
CONFIG_DEBUG_LEAK_ADDRESSES, then that's great, and you won't even have
to change users, you can just change how %p behaves.