linux-kernel - Re: [PATCH v1 1/5] devres: Introduce devm_kmemdup

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Message-ID: <Z0SS3cO4acfgz0iQ@black.fi.intel.com>
Date: Mon, 25 Nov 2024 17:08:13 +0200
From: Raag Jadav <raag.jadav@...el.com>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: Dmitry Torokhov <dmitry.torokhov@...il.com>, gregkh@...uxfoundation.org,
	linus.walleij@...aro.org, mika.westerberg@...ux.intel.com,
	broonie@...nel.org, pierre-louis.bossart@...ux.dev,
	linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-input@...r.kernel.org, linux-sound@...r.kernel.org
Subject: Re: [PATCH v1 1/5] devres: Introduce devm_kmemdup_array()

On Mon, Nov 25, 2024 at 09:49:22AM +0200, Andy Shevchenko wrote:
> On Sun, Nov 24, 2024 at 07:03:36AM +0000, Dmitry Torokhov wrote:
> > On Sun, Nov 24, 2024 at 01:35:23AM +0530, Raag Jadav wrote:
> > > Introduce '_array' variant of devm_kmemdup() for the users which lack
> > > multiplication overflow check.
> > 
> > I am not sure that this new helper is needed. Unlike allocators for
> > brand new objects, such as kmalloc_array(), devm_kmemdup() makes a copy
> > of already existing object, which is supposed to be a valid object and
> > therefore will have a reasonable size. So there should be no chance for
> > hitting this overflow unless the caller is completely confused and calls
> > devm_kmemdup() with random arguments (in which case all bets are off).
> 
> Don't we want to have a code more robust even if all what you say applies?
> Also this makes the call consistent with zillions of others from the alloc
> family of calls in the Linux kernel.

Agree. Although shooting in the foot is never the expectation, it is
atleast better than having to debug such unexpected cases.

Raag