Re: [PATCH] arm: dma-mapping: Fix mapping size value

[Marek Szyprowski <m.szyprowski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>]

Hello,

On 2014-04-21 08:47, Ritesh Harjani wrote:
> 68efd7d2fb("arm: dma-mapping: remove order parameter from
> arm_iommu_create_mapping()") is causing kernel panic
> because it wrongly sets the value of mapping->size:
>
> Unable to handle kernel NULL pointer dereference at virtual
> address 000000a0
> pgd = e7a84000
> [000000a0] *pgd=00000000
> ...
> PC is at bitmap_clear+0x48/0xd0
> LR is at __iommu_remove_mapping+0x130/0x164
>
> Fix it by correcting mapping->size value.
>
> Signed-off-by: Ritesh Harjani <ritesh.harjani-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> Acked-by: Laurent Pinchart <laurent.pinchart-ryLnwIuWjnjg/C1BVhZhaw@public.gmane.org>

Thanks for spotting this issue! I'm really sorry for introducing it. I 
will push it to the fixes branch asap.

> ---
>   arch/arm/mm/dma-mapping.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
> index f62aa06..6b00be1 100644
> --- a/arch/arm/mm/dma-mapping.c
> +++ b/arch/arm/mm/dma-mapping.c
> @@ -1963,8 +1963,8 @@ arm_iommu_create_mapping(struct bus_type *bus, dma_addr_t base, size_t size)
>   	mapping->nr_bitmaps = 1;
>   	mapping->extensions = extensions;
>   	mapping->base = base;
> -	mapping->size = bitmap_size << PAGE_SHIFT;
>   	mapping->bits = BITS_PER_BYTE * bitmap_size;
> +	mapping->size = mapping->bits << PAGE_SHIFT;
>   
>   	spin_lock_init(&mapping->lock);

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland