From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,RDNS_NONE,SPF_HELO_NONE,SPF_NONE autolearn=no autolearn_force=no version=3.4.0 Received: from foss.arm.com ([217.140.110.172]:51480 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726314AbgCKQTE (ORCPT ); Wed, 11 Mar 2020 12:19:04 -0400 Subject: Re: [PATCH] device core: fix dma_mask handling in platform_device_register_full To: Christoph Hellwig , torvalds@linux-foundation.org, gregkh@linuxfoundation.org Cc: aros@gmx.com, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org References: <20200311160710.376090-1-hch@lst.de> From: Robin Murphy Message-ID: <8dda3bc4-d64c-e532-b992-614be8a2ab7c@arm.com> Date: Wed, 11 Mar 2020 16:19:01 +0000 MIME-Version: 1.0 In-Reply-To: <20200311160710.376090-1-hch@lst.de> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: On 11/03/2020 4:07 pm, Christoph Hellwig wrote: > Ever since the generic platform device code started allocating DMA masks > itself the code to allocate and leak a private DMA mask in > platform_device_register_full has been superflous. More so the fact that > it unconditionally frees the DMA mask allocation in the failure path > can lead to slab corruption if the function fails later on for a device > where it didn't allocate the mask. Just remove the offending code. I'm sure I mentioned this in passing at the time, but only in the context of a cleanup; I never noticed it could be cause for an actual bug :) Reviewed-by: Robin Murphy > Fixes: cdfee5623290 ("driver core: initialize a default DMA mask for platform device") > Reported-by: Artem S. Tashkinov > Tested-by: Artem S. Tashkinov > --- > drivers/base/platform.c | 14 -------------- > 1 file changed, 14 deletions(-) > > diff --git a/drivers/base/platform.c b/drivers/base/platform.c > index 7fa654f1288b..47d3e6187a1c 100644 > --- a/drivers/base/platform.c > +++ b/drivers/base/platform.c > @@ -662,19 +662,6 @@ struct platform_device *platform_device_register_full( > pdev->dev.of_node_reused = pdevinfo->of_node_reused; > > if (pdevinfo->dma_mask) { > - /* > - * This memory isn't freed when the device is put, > - * I don't have a nice idea for that though. Conceptually > - * dma_mask in struct device should not be a pointer. > - * See http://thread.gmane.org/gmane.linux.kernel.pci/9081 > - */ > - pdev->dev.dma_mask = > - kmalloc(sizeof(*pdev->dev.dma_mask), GFP_KERNEL); > - if (!pdev->dev.dma_mask) > - goto err; > - > - kmemleak_ignore(pdev->dev.dma_mask); > - > *pdev->dev.dma_mask = pdevinfo->dma_mask; > pdev->dev.coherent_dma_mask = pdevinfo->dma_mask; > } > @@ -700,7 +687,6 @@ struct platform_device *platform_device_register_full( > if (ret) { > err: > ACPI_COMPANION_SET(&pdev->dev, NULL); > - kfree(pdev->dev.dma_mask); > platform_device_put(pdev); > return ERR_PTR(ret); > } >