linux-kernel - Re: [PATCH] nvdimm: Replace the usage of a variable by a direct function call in nd_pfn

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Message-ID: <ZDmKKadGjEwKMCcY@smile.fi.intel.com>
Date:   Fri, 14 Apr 2023 20:15:21 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Markus Elfring <Markus.Elfring@....de>
Cc:     kernel-janitors@...r.kernel.org, nvdimm@...ts.linux.dev,
        Dan Williams <dan.j.williams@...el.com>,
        Dave Jiang <dave.jiang@...el.com>,
        Ira Weiny <ira.weiny@...el.com>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        Vishal Verma <vishal.l.verma@...el.com>, cocci@...ia.fr,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] nvdimm: Replace the usage of a variable by a direct
 function call in nd_pfn_validate()

On Fri, Apr 14, 2023 at 12:12:37PM +0200, Markus Elfring wrote:
> Date: Fri, 14 Apr 2023 12:01:15 +0200
> 
> The address of a data structure member was determined before
> a corresponding null pointer check in the implementation of
> the function “nd_pfn_validate”.
> 
> Thus avoid the risk for undefined behaviour by replacing the usage of
> the local variable “parent_uuid” by a direct function call within
> a later condition check.

> This issue was detected by using the Coccinelle software.
> 
> Fixes: d1c6e08e7503649e4a4f3f9e700e2c05300b6379 ("libnvdimm/labels: Add uuid helpers")

Same issues as per patch 1.

...

> -	if (memcmp(pfn_sb->parent_uuid, parent_uuid, 16) != 0)
> +	if (memcmp(pfn_sb->parent_uuid, nd_dev_to_uuid(&ndns->dev), 16) != 0)

If parent_uuid is of uuid_t type, you better to replace memcmp() with
uuid_equal().

>  		return -ENODEV;

-- 
With Best Regards,
Andy Shevchenko