linux-kernel - Re: [PATCH 2/2] livepatch: Fix the bug if the function name is larger than KSYM_NAME

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Message-ID: <20150414151110.GL4412@treble.hsd1.ky.comcast.net>
Date:	Tue, 14 Apr 2015 10:11:10 -0500
From:	Josh Poimboeuf <jpoimboe@...hat.com>
To:	Minfei Huang <minfei.huang@...mail.com>
Cc:	sjenning@...hat.com, jkosina@...e.cz, vojtech@...e.cz,
	live-patching@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] livepatch: Fix the bug if the function name is
 larger than KSYM_NAME_LEN-1

On Tue, Apr 14, 2015 at 01:45:49PM +0800, Minfei Huang wrote:
> On 04/14/15 at 12:32P, Josh Poimboeuf wrote:
> > On Tue, Apr 14, 2015 at 01:29:50PM +0800, Minfei Huang wrote:
> > > 
> > > For end user, they may know litter about restriction of kallsyms and
> > > livepatch. How can they know the restriction that function name is
> > > limited to 127?
> > 
> > As I mentioned above, I think kallsyms.c should fail the build if it
> > encounters a symbol longer than KSYM_NAME_LEN.
> > 
> 
> I dont think it is a good idea to handle this case like that. The
> function name is only for human recognization. Why the compiler fails
> to build it?

Well, the function name isn't only for human recognition.  kpatch-build
generates patch modules automatically.  It assumes that the compiled
function name matches the kallsyms name.  And I'd guess that a lot of
other code (both in-kernel and user space tools) make the same
assumption.

Not to mention that most humans would also make the same assumption...

-- 
Josh
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