lkml.org 
[lkml]   [2020]   [Sep]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] dma-direct: Fix potential NULL pointer dereference
From
Date


On 2020-09-15 10:07 a.m., Christoph Hellwig wrote:
> 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.
>

Thanks, Christoph for your comment. The caller already fixed the null
pointer in the latest v5.9-rc5. I am thinking that if we had used the
dma_get_mask(), the kernel couldn't panic and could properly print out
the warning message.

Thomas

\
 
 \ /
  Last update: 2020-09-16 02:26    [W:0.170 / U:0.316 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site