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,
hch@lst.de
Subject: Re: [PATCH] dma-direct: Fix potential NULL pointer dereference
Date: Tue, 15 Sep 2020 16:07:19 +0200 [thread overview]
Message-ID: <20200915140719.GA14831@lst.de> (raw)
In-Reply-To: <1600178594-22801-1-git-send-email-thomas.tai@oracle.com>
On Tue, Sep 15, 2020 at 08:03:14AM -0600, Thomas Tai wrote:
> When booting the kernel v5.9-rc4 on a VM, the kernel would panic when
> printing a warning message in swiotlb_map(). It is because dev->dma_mask
> can potentially be a null pointer. Using the dma_get_mask() macro can
> avoid the NULL pointer dereference.
dma_mask must not be zero. This means drm is calling DMA API functions
on something weird. This needs to be fixed in the caller.
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WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Thomas Tai <thomas.tai@oracle.com>
Cc: konrad.wilk@oracle.com, m.szyprowski@samsung.com, hch@lst.de,
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 16:07:19 +0200 [thread overview]
Message-ID: <20200915140719.GA14831@lst.de> (raw)
In-Reply-To: <1600178594-22801-1-git-send-email-thomas.tai@oracle.com>
On Tue, Sep 15, 2020 at 08:03:14AM -0600, Thomas Tai wrote:
> When booting the kernel v5.9-rc4 on a VM, the kernel would panic when
> printing a warning message in swiotlb_map(). It is because dev->dma_mask
> can potentially be a null pointer. Using the dma_get_mask() macro can
> avoid the NULL pointer dereference.
dma_mask must not be zero. This means drm is calling DMA API functions
on something weird. This needs to be fixed in the caller.
next prev parent reply other threads:[~2020-09-15 14:07 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 [this message]
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
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
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