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SubjectRe: [PATCH v2] dma-mapping: Use dma_get_mask in dma_addressing_limited
On Mon, Jul 22, 2019 at 06:51:49PM +0200, Eric Auger wrote:
> We currently have cases where the dma_addressing_limited() gets
> called with dma_mask unset. This causes a NULL pointer dereference.
>
> Use dma_get_mask() accessor to prevent the crash.
>
> Fixes: b866455423e0 ("dma-mapping: add a dma_addressing_limited helper")
> Signed-off-by: Eric Auger <eric.auger@redhat.com>

Acked-by: Michael S. Tsirkin <mst@redhat.com>

If possible I really prefer this approach: avoids changing all callers
and uses documented interfaces.

> ---
>
> v1 -> v2:
> - was [PATCH 1/2] dma-mapping: Protect dma_addressing_limited
> against NULL dma_mask
> - Use dma_get_mask
> ---
> include/linux/dma-mapping.h | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
> index e11b115dd0e4..f7d1eea32c78 100644
> --- a/include/linux/dma-mapping.h
> +++ b/include/linux/dma-mapping.h
> @@ -689,8 +689,8 @@ static inline int dma_coerce_mask_and_coherent(struct device *dev, u64 mask)
> */
> static inline bool dma_addressing_limited(struct device *dev)
> {
> - return min_not_zero(*dev->dma_mask, dev->bus_dma_mask) <
> - dma_get_required_mask(dev);
> + return min_not_zero(dma_get_mask(dev), dev->bus_dma_mask) <
> + dma_get_required_mask(dev);
> }
>
> #ifdef CONFIG_ARCH_HAS_SETUP_DMA_OPS
> --
> 2.20.1

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