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    SubjectRe: [PATCH] dma: fix up broken comparison in dma_alloc_from_coherent
    On Wed, 21 Jan 2009 17:11:19 +0900
    Paul Mundt <lethal@linux-sh.org> wrote:

    > @@ -118,31 +118,32 @@ int dma_alloc_from_coherent(struct device *dev, ssize_t size,
    > mem = dev->dma_mem;
    > if (!mem)
    > return 0;
    > - if (unlikely(size > mem->size))
    > - return 0;
    > +
    > + *ret = NULL;
    > +
    > + if (unlikely(size > (mem->size << PAGE_SHIFT)))
    > + goto err;

    Looks a bit broken on 64-bit.

    `size' is ssize_t (long).

    `mem->size' is `int'.

    The left shift can overflow and cause badnesses.

    > + *dma_handle = mem->device_base + (pageno << PAGE_SHIFT);
    > + *ret = mem->virt_base + (pageno << PAGE_SHIFT);

    Ditto.


    Maybe it's a can't-happen (why?), but...


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