From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gen Zhang Subject: Re: [PATCH] tegra_wm9712: Fix a memory leaking bug in tegra_wm9712_driver_probe() Date: Fri, 24 May 2019 22:33:09 +0800 Message-ID: <20190524143309.GA8631@zhanggen-UX430UQ> References: <20190524005014.GA2289@zhanggen-UX430UQ> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Jon Hunter Cc: lgirdwood@gmail.com, perex@perex.cz, alsa-devel@alsa-project.org, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-tegra@vger.kernel.org On Fri, May 24, 2019 at 09:33:13AM +0100, Jon Hunter wrote: > > On 24/05/2019 01:50, Gen Zhang wrote: > > In tegra_wm9712_driver_probe(), 'machine->codec' is allocated by > > platform_device_alloc(). When it is NULL, function returns ENOMEM. > > However, 'machine' is allocated by devm_kzalloc() before this site. > > Thus we should free 'machine' before function ends to prevent memory > > leaking. > > Memory allocated by devm_xxx() is automatically freed on failure so this > is not correct. Thanks for your comments, Jon. But after I examined the code, I am still confused about the usage of devm_kmalloc(). You can kindly refer to hisi_sas_debugfs_init() in drivers/scsi/hisi_sas/hisi_sas_main.c. And devm_kfree() is used to free a memory allocated by devm_kmalloc(). And I found other situations similar to this in other files. So, I hope you can give me some guidance on this. Thanks! > > > Further, we should free 'machine->util_data', 'machine->codec' and > > 'machine' before this function normally ends to prevent memory leaking. > > This is also incorrect. Why would we free all resources after > successfully initialising the driver? I re-checked this part, and it is totally incorrect. It should be deleted. Thanks Gen