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Date: Fri, 18 Mar 2016 16:02:48 +0300
From: Dan Carpenter <dan.carpenter@oracle.com>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Christian Gromm <christian.gromm@microchip.com>,
        Greg KH <gregkh@linuxfoundation.org>,
        driverdevel <devel@driverdev.osuosl.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: staging: most: warning: =?utf-8?B?4oCY?= =?utf-8?B?bWJv4oCZ?=
 may be used uninitialized in this function
Message-ID: <20160318130248.GD30221@mwanda>
References: <CAMuHMdVKbyE0rGUgZw9htqNG1uNx_hBR_G+5BEFEwu8QTa9sfg@mail.gmail.com>
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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