Re: possible memory leak in commands/nand.c?

[Sascha Hauer <s.hauer@pengutronix.de>]

On Mon, Dec 21, 2009 at 04:17:29AM -0500, Robert P. J. Day wrote:
> On Mon, 21 Dec 2009, Sascha Hauer wrote:
> 
> ... snip ...
> 
> > Yes, indeed, that's a memory hole here. The following should fix
> > this. Thanks for noting.
> >
> > Sascha
> >
> >
> > >From 4e4b03cd61808383a98cb1d10a47025e1909e0bd Mon Sep 17 00:00:00 2001
> > From: Sascha Hauer <s.hauer@pengutronix.de>
> > Date: Mon, 21 Dec 2009 09:41:52 +0100
> > Subject: [PATCH] commands/nand.c: Fix memory hole
> >
> > Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> > ---
> >  commands/nand.c |   22 +++++++++++++++++-----
> >  1 files changed, 17 insertions(+), 5 deletions(-)
> >
> > diff --git a/commands/nand.c b/commands/nand.c
> > index cbf1058..55b89af 100644
> > --- a/commands/nand.c
> > +++ b/commands/nand.c
> > @@ -224,31 +224,37 @@ static struct file_operations nand_bb_ops = {
> >  int dev_add_bb_dev(char *path, const char *name)
> >  {
> >  	struct nand_bb *bb;
> > -	int ret;
> > +	int ret = -ENOMEM;
> >  	struct stat s;
> >
> >  	bb = xzalloc(sizeof(*bb));
> >  	bb->devname = asprintf("/dev/%s", basename(path));
> > +	if (!bb->devname)
> > +		goto out1;
> > +
> >  	if (name)
> >  		bb->cdev.name = strdup(name);
> >  	else
> >  		bb->cdev.name = asprintf("%s.bb", basename(path));
> >
> > +	if (!bb->cdev.name)
> > +		goto out2;
> > +
> >  	ret = stat(bb->devname, &s);
> >  	if (ret)
> > -		goto free_out;
> > +		goto out3;
> >
> >  	bb->raw_size = s.st_size;
> >
> >  	bb->fd = open(bb->devname, O_RDWR);
> >  	if (bb->fd < 0) {
> >  		ret = -ENODEV;
> > -		goto free_out;
> > +		goto out3;
> >  	}
> >
> >  	ret = ioctl(bb->fd, MEMGETINFO, &bb->info);
> >  	if (ret)
> > -		goto free_out;
> > +		goto out4;
> >
> >  	nand_bb_calc_size(bb);
> >  	bb->cdev.ops = &nand_bb_ops;
> > @@ -258,7 +264,13 @@ int dev_add_bb_dev(char *path, const char *name)
> >
> >  	return 0;
> >
> > -free_out:
> > +out4:
> > +	close(bb->fd);
> > +out3:
> > +	free(bb->cdev.name);
> > +out2:
> > +	free(bb->devname);
> > +out1:
> >  	free(bb);
> >  	return ret;
> >  }
> 
>   i'm not sure this required distinguishing between every one of those
> cases since the initial space was allocated with xzalloc(),
> guaranteeing it would be zero-filled, and freeing a NULL pointer is
> supposed to be a no-op.
> 
>   so it would have been simpler to just
> 
>   free(bb->devname);		# might be NULL, no problem
>   free(bb->cdev.name);		# same here
>   free(bb);

Yes, you're right. OTOH we probably do not save anything by removing
the different jump labels.

Sascha

> 

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