linux-kernel - Re: [PATCH] staging: unisys: virtpci: virtpci: Fix for possible null pointer dereference

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Message-ID: <20150130123942.GY6456@mwanda>
Date:	Fri, 30 Jan 2015 15:39:42 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	Rickard Strandqvist <rickard_strandqvist@...ctrumdigital.se>
Cc:	Benjamin Romer <benjamin.romer@...sys.com>,
	David Kershner <david.kershner@...sys.com>,
	devel@...verdev.osuosl.org,
	Erik Arfvidson <erik.arfvidson@...sys.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	sparmaintainer@...sys.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] staging: unisys: virtpci: virtpci: Fix for possible null
 pointer dereference

Run your patches through checkpatch.pl.

On Thu, Jan 29, 2015 at 07:50:26PM +0100, Rickard Strandqvist wrote:
> -	if (dprivate != NULL)
> +	if (dprivate != NULL) {

This is a double negative.  Just say "if (dprivate) {".  Actually just
reverse the test and remove the bogus printk.  Say:

	if (!dprivate)
		return 0;

But *actually* just remove the test entirely because it can never be
NULL.  Same for virtpci_driver_attr_store().

Btw, if you have the smatch cross function database set up then you can
figure out this sort of thing by using:

$ smdb.py virtpci_driver_attr_store

It says that:

     fs/sysfs/file.c |       sysfs_kf_write | (struct sysfs_ops)->store |  PARAM_VALUE |  0 | $ | 4096-2117777777777777777

So this is called from sysfs_kf_write() and parameter zero is a valid
pointer.

regards,
dan carpenter

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