linux-kernel - Re: [PATCH 1/7] livepatch: Apply vmlinux-specific KLP relocations early

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Message-ID: <20200415162911.k3kuqi5dqmngise7@treble>
Date:   Wed, 15 Apr 2020 11:29:11 -0500
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Miroslav Benes <mbenes@...e.cz>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        live-patching@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jessica Yu <jeyu@...nel.org>
Subject: Re: [PATCH 1/7] livepatch: Apply vmlinux-specific KLP relocations
 early

On Wed, Apr 15, 2020 at 04:30:15PM +0200, Miroslav Benes wrote:
> > From: Josh Poimboeuf <jpoimboe@...hat.com>
> > Subject: [PATCH] livepatch: Disallow vmlinux.ko
> > 
> > This is purely a theoretical issue, but if there were a module named
> 
> OT: "if there were"... subjunctive?

I had to google "subjunctive", but yes that seems to be it :-)

It means "if, hypothetically, a module named vmlinux.ko existed"...

> > vmlinux.ko, the livepatch relocation code wouldn't be able to
> > distinguish between vmlinux-specific and vmlinux.o-specific KLP
> > relocations.
> > 
> > If CONFIG_LIVEPATCH is enabled, don't allow a module named vmlinux.ko.
> 
> Yup, there is no such check nowadays. I always struggle to find the right 
> balance between being overprotective and letting the user shoot themselves 
> in their foot if they want to. But it does not hurt, so ack to that.

Yeah, and it does seem very unlikely to have a vmlinux.ko, but
especially OOT modules do some crazy things and you never know...

-- 
Josh