linux-kernel - Re: staging: most: warning: ‘mbo’ may be used uninitialized in this function

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Message-ID: <20160318130248.GD30221@mwanda>
Date:	Fri, 18 Mar 2016 16:02:48 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:	Christian Gromm <christian.gromm@...rochip.com>,
	Greg KH <gregkh@...uxfoundation.org>,
	driverdevel <devel@...verdev.osuosl.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: staging: most: warning: ‘mbo’
 may be used uninitialized in this function

On Fri, Mar 18, 2016 at 01:41:19PM +0100, Geert Uytterhoeven wrote:
> > @@ -249,11 +246,7 @@ aim_read(struct file *filp, char __user *buf, size_t count, loff_t *offset)
> >         struct aim_channel *c = filp->private_data;
> >
> >         mutex_lock(&c->io_mutex);
> > -       if (c->stacked_mbo) {
> > -               mbo = c->stacked_mbo;
> > -               goto start_copy;
> > -       }
> > -       while ((!kfifo_out(&c->fifo, &mbo, 1)) && (c->dev)) {
> > +       while (c->dev && !kfifo_peek(&c->fifo, &mbo)) {
> 
> drivers/staging/most/aim-cdev/cdev.c:241: warning: ‘mbo’ may be used
> uninitialized in this function
> 
> From looking at the code, it's not obvious to me if this is a false
> positive or not.
> Can it happen that mbo is not initialized fully, e.g. if less than sizeof(mbo)
> bytes have been read from the kfifo?
> 
> Other callers initialize the pointer to NULL, and check the returned length.
> 

It looks like a false positive to me.

regards,
dan carpenter