Messages in this thread Patch in this message | | | From | Geert Uytterhoeven <> | Date | Tue, 17 Apr 2018 16:04:27 +0200 | Subject | Re: [PATCH] sh: mm: Fix unprotected access to struct device |
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Hi Jacopo,
Thanks for your patch!
On Tue, Apr 17, 2018 at 3:35 PM, Jacopo Mondi <jacopo+renesas@jmondi.org> 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 <geert+renesas@glider.be>
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
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