linux-kernel - Re: [PATCH] regmap: debugfs: potentially duplicate the name string of the config

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Date:   Tue, 8 Sep 2020 18:07:56 +0200
From:   Dafna Hirschfeld <dafna.hirschfeld@...labora.com>
To:     Mark Brown <broonie@...nel.org>
Cc:     linux-kernel@...r.kernel.org, rafael@...nel.org,
        gregkh@...uxfoundation.org, enric.balletbo@...labora.com,
        kernel@...labora.com, dafna3@...il.com
Subject: Re: [PATCH] regmap: debugfs: potentially duplicate the name string of
 the config

Hi, thank you for the fast review,

Am 08.09.20 um 17:35 schrieb Mark Brown:
> On Tue, Sep 08, 2020 at 05:28:59PM +0200, Dafna Hirschfeld wrote:
>> In function regmap_debugfs_init the name of the regmap_config is assigned
>> in a node of regmap_debugfs_early_list to be used later after regmap
>> is initialized. It is unknown how and when the name is allocated and freed.
>> Therefore the name should be copied to the node using 'kstrdup_const'.
> 
> It does not follow that the name should be copied, it equally follows
> (and is expected by the API given that the common case is that the name
> is a static string assigned at build time) that the caller should not
> free the string while the regmap is active.

I see that the same copy is already done in function __regmap_init in drivers/base/regmap/regmap.c
added in patch 8253bb3f82554 "regmap: potentially duplicate the name string stored in regmap"
so I thought I'll do the same.

> 
>> This fixes an error
>> "debugfs: Directory 'dummy-' with parent 'regmap' already present!"
>> where the name was freed in function of_syscon_register before
>> it was accessed.
> 
> Fix the caller.  It is *very* much unclear to me why a syscon would be
> assigning a name for a regmap it creates in the first place.

I'll have a deeper look.

Thanks,
Dafna

>