From: Thomas Tai <thomas.tai@oracle.com>
To: Christoph Hellwig <hch@lst.de>
Cc: iommu@lists.linux-foundation.org, robin.murphy@arm.com,
linux-kernel@vger.kernel.org, konrad.wilk@oracle.com
Subject: Re: [PATCH] dma-direct: Fix potential NULL pointer dereference
Date: Tue, 15 Sep 2020 11:12:28 -0400 [thread overview]
Message-ID: <9a819530-365b-9982-c9c9-ad20d6c8149e@oracle.com> (raw)
In-Reply-To: <20200915150929.GA19770@lst.de>
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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next prev parent reply other threads:[~2020-09-15 15:14 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-15 14:03 [PATCH] dma-direct: Fix potential NULL pointer dereference Thomas Tai
2020-09-15 14:07 ` Christoph Hellwig
2020-09-15 14:08 ` Christoph Hellwig
2020-09-15 14:11 ` Thomas Tai
2020-09-15 14:26 ` Christoph Hellwig
2020-09-15 14:40 ` Thomas Tai
2020-09-15 15:09 ` Christoph Hellwig
2020-09-15 15:12 ` Thomas Tai [this message]
2020-09-15 20:46 ` Thomas Tai
2020-09-16 6:19 ` Christoph Hellwig
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