netdev - Re: [PATCH 2/7] ethtool: avoid resource leak of strings in do

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Message-ID: <20161004140223.GA12675@tuxdriver.com>
Date:   Tue, 4 Oct 2016 10:02:24 -0400
From:   "John W. Linville" <linville@...driver.com>
To:     Jarod Wilson <jarod@...hat.com>
Cc:     netdev@...r.kernel.org
Subject: Re: [PATCH 2/7] ethtool: avoid resource leak of strings in
 do_gprivflags

On Mon, Oct 03, 2016 at 01:54:26PM -0400, Jarod Wilson wrote:
> On Fri, Sep 30, 2016 at 03:56:16PM -0400, John W. Linville wrote:
> > Coverity issue: 1363119
> > Fixes: e1ee596326ae ("Add support for querying and setting private flags")
> > 
> > Signed-off-by: John W. Linville <linville@...driver.com>
> > ---
> >  ethtool.c | 18 +++++++++++++-----
> >  1 file changed, 13 insertions(+), 5 deletions(-)
> > 
> > diff --git a/ethtool.c b/ethtool.c
> > index aa3ef5ed2f75..0885a61097ad 100644
> > --- a/ethtool.c
> > +++ b/ethtool.c
> > @@ -4205,7 +4205,7 @@ static int do_gprivflags(struct cmd_context *ctx)
> >  	struct ethtool_gstrings *strings;
> >  	struct ethtool_value flags;
> >  	unsigned int i;
> > -	int max_len = 0, cur_len;
> > +	int max_len = 0, cur_len, rc;
> >  
> >  	if (ctx->argc != 0)
> >  		exit_bad_args();
> > @@ -4215,11 +4215,13 @@ static int do_gprivflags(struct cmd_context *ctx)
> >  				1);
> >  	if (!strings) {
> >  		perror("Cannot get private flag names");
> > -		return 1;
> > +		rc = 1;
> > +		goto err;
> 
> This goto looks redundant, since all you're doing at err is re-checking if
> strings is non-null to free it.

True, the original return is just as good there. And since strings
is non-NULL for everything after that, the NULL check at error can
be eliminated as well...

Thanks!

John

> >  	if (strings->len == 0) {
> >  		fprintf(stderr, "No private flags defined\n");
> > -		return 1;
> > +		rc = 1;
> > +		goto err;
> >  	}
> >  	if (strings->len > 32) {
> >  		/* ETHTOOL_GPFLAGS can only cover 32 flags */
> > @@ -4230,7 +4232,8 @@ static int do_gprivflags(struct cmd_context *ctx)
> >  	flags.cmd = ETHTOOL_GPFLAGS;
> >  	if (send_ioctl(ctx, &flags)) {
> >  		perror("Cannot get private flags");
> > -		return 1;
> > +		rc = 1;
> > +		goto err;
> >  	}
> >  
> >  	/* Find longest string and align all strings accordingly */
> > @@ -4248,7 +4251,12 @@ static int do_gprivflags(struct cmd_context *ctx)
> >  		       (const char *)strings->data + i * ETH_GSTRING_LEN,
> >  		       (flags.data & (1U << i)) ? "on" : "off");
> >  
> > -	return 0;
> > +	rc = 0;
> > +
> > +err:
> > +	if (strings)
> > +		free(strings);
> > +	return rc;
> >  }
> >  
> >  static int do_sprivflags(struct cmd_context *ctx)
> > -- 
> > 2.7.4
> > 
> 
> -- 
> Jarod Wilson
> jarod@...hat.com
> 
> 
> 

-- 
John W. Linville		Someday the world will need a hero, and you
linville@...driver.com			might be all we have.  Be ready.