Re: [PATCH 4.19 016/125] media: pci: ttpci: av7110: fix possible buffer overflow caused by bad DMA value in debiirq()

[Greg Kroah-Hartman]

On Tue, Sep 01, 2020 at 05:25:12PM +0100, Sean Young wrote:
> Greg,
> 
> On Tue, Sep 01, 2020 at 05:09:31PM +0200, Greg Kroah-Hartman wrote:
> > From: Jia-Ju Bai <baijiaju@xxxxxxxxxxxxxxx>
> > 
> > [ Upstream commit 6499a0db9b0f1e903d52f8244eacc1d4be00eea2 ]
> > 
> > The value av7110->debi_virt is stored in DMA memory, and it is assigned
> > to data, and thus data[0] can be modified at any time by malicious
> > hardware. In this case, "if (data[0] < 2)" can be passed, but then
> > data[0] can be changed into a large number, which may cause buffer
> > overflow when the code "av7110->ci_slot[data[0]]" is used.
> > 
> > To fix this possible bug, data[0] is assigned to a local variable, which
> > replaces the use of data[0].
> 
> See the discussion here:
> 
> https://lkml.org/lkml/2020/8/31/479
> 
> It does not seem worthwhile merging to the stable trees.

It doesn't hurt either :)

thanks,

greg k-h