From mboxrd@z Thu Jan 1 00:00:00 1970 From: Geert Uytterhoeven Date: Tue, 17 Apr 2018 14:04:27 +0000 Subject: Re: [PATCH] sh: mm: Fix unprotected access to struct device Message-Id: List-Id: References: <1523972123-5700-1-git-send-email-jacopo+renesas@jmondi.org> In-Reply-To: <1523972123-5700-1-git-send-email-jacopo+renesas@jmondi.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Jacopo Mondi Cc: Yoshinori Sato , Rich Felker , Thomas Petazzoni , Robin Murphy , Linux-Renesas , Linux-sh list , Linux Kernel Mailing List Hi Jacopo, Thanks for your patch! On Tue, Apr 17, 2018 at 3:35 PM, Jacopo Mondi wrote: > With commit ce88313069c36eef80f21fd7 ("arch/sh: make the DMA mapping > operations observe dev->dma_pfn_offset") the generic DMA allocation > function on which the SH 'dma_alloc_coherent()' function relies on, > access the 'dma_pfn_offset' field of struct device. accesses > Unfortunately the 'dma_generic_alloc_coherent()' function is called from > several places with a NULL struct device argument, halting the CPU > during the boot process. > > This patch fixes the issue protecting access to dev->dma_pfn_offset, by protecting access to the > with a trivial check for validity. It also passes a valid 'struct device' > in the 'platform_resource_setup_memory' function which is the main user > of 'dma_alloc_coherent()', and inserting a WARN_ON() check to make future > (and existing) bogus users of this function they're should provide a valid drop "they're should"? > 'struct device' whenever possible. > --- a/arch/sh/mm/consistent.c > +++ b/arch/sh/mm/consistent.c > @@ -39,6 +39,8 @@ void *dma_generic_alloc_coherent(struct device *dev, size_t size, > void *ret, *ret_nocache; > int order = get_order(size); > > + WARN_ON(!dev); > + > gfp |= __GFP_ZERO; > > ret = (void *)__get_free_pages(gfp, order); > @@ -59,7 +61,9 @@ void *dma_generic_alloc_coherent(struct device *dev, size_t size, > > split_page(pfn_to_page(virt_to_phys(ret) >> PAGE_SHIFT), order); > > - *dma_handle = virt_to_phys(ret) - PFN_PHYS(dev->dma_pfn_offset); > + *dma_handle = virt_to_phys(ret); > + if (dev) > + *dma_handle -= PFN_PHYS(dev->dma_pfn_offset); I would keep the WARN_ON() and the (ideally unneeded) dev check as close to each other as possible: if (!WARN_ON(!dev)) *dma_handle -= PFN_PHYS(dev->dma_pfn_offset); > > return ret_nocache; > } > @@ -69,9 +73,14 @@ void dma_generic_free_coherent(struct device *dev, size_t size, > unsigned long attrs) > { > int order = get_order(size); > - unsigned long pfn = (dma_handle >> PAGE_SHIFT) + dev->dma_pfn_offset; > + unsigned long pfn = (dma_handle >> PAGE_SHIFT); > int k; > > + WARN_ON(!dev); > + > + if (dev) > + pfn += dev->dma_pfn_offset; if (!WARN_ON(!dev)) pfn += dev->dma_pfn_offset; > + > for (k = 0; k < (1 << order); k++) > __free_pages(pfn_to_page(pfn + k), 0); Reviewed-by: Geert Uytterhoeven Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752570AbeDQOEb (ORCPT ); Tue, 17 Apr 2018 10:04:31 -0400 Received: from mail-ua0-f194.google.com ([209.85.217.194]:44382 "EHLO mail-ua0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751270AbeDQOE3 (ORCPT ); Tue, 17 Apr 2018 10:04:29 -0400 X-Google-Smtp-Source: AIpwx4+3sQNh2FB82JAIHphQ9d1YmtJB880buMh2A9wW+OnNms6O4jDftpNj1PyeaE/3wQsRXOyll6dM57GA4uEHCGo= MIME-Version: 1.0 In-Reply-To: <1523972123-5700-1-git-send-email-jacopo+renesas@jmondi.org> References: <1523972123-5700-1-git-send-email-jacopo+renesas@jmondi.org> From: Geert Uytterhoeven Date: Tue, 17 Apr 2018 16:04:27 +0200 X-Google-Sender-Auth: 16_Wvygr1pCXa4LEQ3mqhWwwPmk Message-ID: Subject: Re: [PATCH] sh: mm: Fix unprotected access to struct device To: Jacopo Mondi Cc: Yoshinori Sato , Rich Felker , Thomas Petazzoni , Robin Murphy , Linux-Renesas , Linux-sh list , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Jacopo, Thanks for your patch! On Tue, Apr 17, 2018 at 3:35 PM, Jacopo Mondi wrote: > With commit ce88313069c36eef80f21fd7 ("arch/sh: make the DMA mapping > operations observe dev->dma_pfn_offset") the generic DMA allocation > function on which the SH 'dma_alloc_coherent()' function relies on, > access the 'dma_pfn_offset' field of struct device. accesses > Unfortunately the 'dma_generic_alloc_coherent()' function is called from > several places with a NULL struct device argument, halting the CPU > during the boot process. > > This patch fixes the issue protecting access to dev->dma_pfn_offset, by protecting access to the > with a trivial check for validity. It also passes a valid 'struct device' > in the 'platform_resource_setup_memory' function which is the main user > of 'dma_alloc_coherent()', and inserting a WARN_ON() check to make future > (and existing) bogus users of this function they're should provide a valid drop "they're should"? > 'struct device' whenever possible. > --- a/arch/sh/mm/consistent.c > +++ b/arch/sh/mm/consistent.c > @@ -39,6 +39,8 @@ void *dma_generic_alloc_coherent(struct device *dev, size_t size, > void *ret, *ret_nocache; > int order = get_order(size); > > + WARN_ON(!dev); > + > gfp |= __GFP_ZERO; > > ret = (void *)__get_free_pages(gfp, order); > @@ -59,7 +61,9 @@ void *dma_generic_alloc_coherent(struct device *dev, size_t size, > > split_page(pfn_to_page(virt_to_phys(ret) >> PAGE_SHIFT), order); > > - *dma_handle = virt_to_phys(ret) - PFN_PHYS(dev->dma_pfn_offset); > + *dma_handle = virt_to_phys(ret); > + if (dev) > + *dma_handle -= PFN_PHYS(dev->dma_pfn_offset); I would keep the WARN_ON() and the (ideally unneeded) dev check as close to each other as possible: if (!WARN_ON(!dev)) *dma_handle -= PFN_PHYS(dev->dma_pfn_offset); > > return ret_nocache; > } > @@ -69,9 +73,14 @@ void dma_generic_free_coherent(struct device *dev, size_t size, > unsigned long attrs) > { > int order = get_order(size); > - unsigned long pfn = (dma_handle >> PAGE_SHIFT) + dev->dma_pfn_offset; > + unsigned long pfn = (dma_handle >> PAGE_SHIFT); > int k; > > + WARN_ON(!dev); > + > + if (dev) > + pfn += dev->dma_pfn_offset; if (!WARN_ON(!dev)) pfn += dev->dma_pfn_offset; > + > for (k = 0; k < (1 << order); k++) > __free_pages(pfn_to_page(pfn + k), 0); Reviewed-by: Geert Uytterhoeven Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds