All of lore.kernel.org
 help / color / mirror / Atom feed
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.
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Thomas Tai <thomas.tai@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>,
	konrad.wilk@oracle.com, m.szyprowski@samsung.com,
	robin.murphy@arm.com, iommu@lists.linux-foundation.org,
	linux-kernel@vger.kernel.org
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.

  reply	other threads:[~2020-09-15 15:09 UTC|newest]

Thread overview: 20+ 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 14:03 ` Thomas Tai
2020-09-15 14:07 ` Christoph Hellwig
2020-09-15 14:07   ` Christoph Hellwig
2020-09-15 14:08   ` Christoph Hellwig
2020-09-15 14:08     ` Christoph Hellwig
2020-09-15 14:11   ` Thomas Tai
2020-09-15 14:11     ` Thomas Tai
2020-09-15 14:26     ` Christoph Hellwig
2020-09-15 14:26       ` Christoph Hellwig
2020-09-15 14:40       ` Thomas Tai
2020-09-15 14:40         ` Thomas Tai
2020-09-15 15:09         ` Christoph Hellwig [this message]
2020-09-15 15:09           ` Christoph Hellwig
2020-09-15 15:12           ` Thomas Tai
2020-09-15 15:12             ` Thomas Tai
2020-09-15 20:46           ` Thomas Tai
2020-09-15 20:46             ` Thomas Tai
2020-09-16  6:19             ` Christoph Hellwig
2020-09-16  6:19               ` Christoph Hellwig

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200915150929.GA19770@lst.de \
    --to=hch@lst.de \
    --cc=iommu@lists.linux-foundation.org \
    --cc=konrad.wilk@oracle.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=robin.murphy@arm.com \
    --cc=thomas.tai@oracle.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.