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SubjectRe: [PATCH] dma-direct: Fix potential NULL pointer dereference
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On 2020-09-15 11:09 a.m., Christoph Hellwig wrote:
> On Tue, Sep 15, 2020 at 10:40:39AM -0400, Thomas Tai wrote:
>>> +++ b/include/linux/dma-direct.h
>>> @@ -62,9 +62,6 @@ static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size,
>>> {
>>> dma_addr_t end = addr + size - 1;
>>> - if (!dev->dma_mask)
>>> - return false;
>>> -
>>
>> I am concerned that some drivers may rely on this NULL checking. Would you
>> think we can keep this checking and use the following WARN_ON_ONCE()?
>
> dma_capable is not a helper for drivers, but just for dma-direct
> and related code. And this patch adds the checks for the three
> places how we call into the ->map* methods.
>

Ok. That sounds good to me. I will make the suggested changes and run
some tests before sending out the V2 patch.

Thank you,
Thomas

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