From: Christoph Hellwig <hch@lst.de>
To: Thomas Tai <thomas.tai@oracle.com>
Cc: konrad.wilk@oracle.com, linux-kernel@vger.kernel.org,
iommu@lists.linux-foundation.org, robin.murphy@arm.com,
Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH] dma-direct: Fix potential NULL pointer dereference
Date: Tue, 15 Sep 2020 17:09:29 +0200 [thread overview]
Message-ID: <20200915150929.GA19770@lst.de> (raw)
In-Reply-To: <da9ec51d-aab5-695d-e388-5ae7c0bb30ea@oracle.com>
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.
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next prev parent reply other threads:[~2020-09-15 15:09 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 [this message]
2020-09-15 15:12 ` Thomas Tai
2020-09-15 20:46 ` Thomas Tai
2020-09-16 6:19 ` Christoph Hellwig
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