netdev - Re: [PATCH 4/5] misc: fix compiler warning in ifstat and nstat

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Date:   Mon, 30 Nov 2020 09:31:13 -0800
From:   Stephen Hemminger <stephen@...workplumber.org>
To:     David Laight <David.Laight@...LAB.COM>
Cc:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH 4/5] misc: fix compiler warning in ifstat and nstat

On Mon, 30 Nov 2020 09:18:59 +0000
David Laight <David.Laight@...LAB.COM> wrote:

> From: Stephen Hemminger
> > Sent: 30 November 2020 00:22
> > 
> > The code here was doing strncpy() in a way that causes gcc 10
> > warning about possible string overflow. Just use strlcpy() which
> > will null terminate and bound the string as expected.
> > 
> > This has existed since start of git era so no Fixes tag.
> > 
> > Signed-off-by: Stephen Hemminger <stephen@...workplumber.org>
> > ---
> >  misc/ifstat.c | 2 +-
> >  misc/nstat.c  | 3 +--
> >  2 files changed, 2 insertions(+), 3 deletions(-)
> > 
> > diff --git a/misc/ifstat.c b/misc/ifstat.c
> > index c05183d79a13..d4a33429dc50 100644
> > --- a/misc/ifstat.c
> > +++ b/misc/ifstat.c
> > @@ -251,7 +251,7 @@ static void load_raw_table(FILE *fp)
> >  			buf[strlen(buf)-1] = 0;
> >  			if (info_source[0] && strcmp(info_source, buf+1))
> >  				source_mismatch = 1;
> > -			strncpy(info_source, buf+1, sizeof(info_source)-1);
> > +			strlcpy(info_source, buf+1, sizeof(info_source));
> >  			continue;  
> 
> ISTM that once it has done a strlen() it ought to use the length
> for the later copy.
> 
> I don't seem to have the source file (I'm guessing it isn't in the
> normal repo), but is that initial strlen() guaranteed not to return
> zero?
> 
> 	David
> 
> -
> Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
> Registration No: 1397386 (Wales)
> 

All this is in the regular iproute2 repo