linux-kernel - Re: [PATCH] init/main.c: simplify repair_env

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Date:   Fri, 4 May 2018 18:08:37 +0200
From:   Michal Suchánek <msuchanek@...e.de>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     Hari Bathini <hbathini@...ux.vnet.ibm.com>,
        Ingo Molnar <mingo@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Kees Cook <keescook@...omium.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Laura Abbott <lauraa@...eaurora.org>,
        Gargi Sharma <gs051095@...il.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] init/main.c: simplify repair_env_string

On Fri, 4 May 2018 11:40:35 -0400
Steven Rostedt <rostedt@...dmis.org> wrote:

> Cleaning out my INBOX, I stumbled across this old patch.
> 
> On Fri, 15 Dec 2017 22:33:17 +0100
> Michal Suchanek <msuchanek@...e.de> wrote:
> 
> > Quoting characters are now removed from the parameter so value
> > always follows directly after the NUL terminating parameter name.
> > 
> > Signed-off-by: Michal Suchanek <msuchanek@...e.de>
> > ---
> >  init/main.c | 13 ++++---------
> >  1 file changed, 4 insertions(+), 9 deletions(-)
> > 
> > Since the previous "[PATCH v9 3/8] lib/cmdline.c: add backslash
> > support to kernel commandline parsing" adds the memmove in
> > lib/cmdline.c it is now superfluous in init/main.c  
> 
> I don't believe the above patches were ever applied. Were they?

No, they weren't.

The reason to write them was to support the fadump_extra_args argument
with peculiar semantics that required the quoting cleanup in kernel
argument parsing.

A different solution for the fadump memory consumption is in the works
so I dropped this. There was lack of interest from reviewers, too.

Thanks

Michal

> 
> -- Steve
> 
> > 
> > diff --git a/init/main.c b/init/main.c
> > index 1f5fdedbb293..1e5b1dc940d9 100644
> > --- a/init/main.c
> > +++ b/init/main.c
> > @@ -244,15 +244,10 @@ static int __init repair_env_string(char
> > *param, char *val, const char *unused, void *arg)
> >  {
> >  	if (val) {
> > -		/* param=val or param="val"? */
> > -		if (val == param+strlen(param)+1)
> > -			val[-1] = '=';
> > -		else if (val == param+strlen(param)+2) {
> > -			val[-2] = '=';
> > -			memmove(val-1, val, strlen(val)+1);
> > -			val--;
> > -		} else
> > -			BUG();
> > +		int parm_len = strlen(param);
> > +
> > +		param[parm_len] = '=';
> > +		BUG_ON(val != param + parm_len + 1);
> >  	}
> >  	return 0;
> >  }  
>