linux-kernel - Re: Re: [PATCH v3] serial: pch_uart: potential dereference of null pointer

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Date:   Thu, 16 Dec 2021 16:24:36 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Jiasheng Jiang <jiasheng@...as.ac.cn>
Cc:     jirislaby@...nel.org, linux-serial@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: Re: [PATCH v3] serial: pch_uart: potential dereference of null
 pointer

On Thu, Dec 16, 2021 at 11:05:39PM +0800, Jiasheng Jiang wrote:
> On Thu, Dec 16, 2021 at 10:36:35PM +0800, Greg KH wrote:
> >> The return value of dma_alloc_coherent() needs to be checked.
> >> To avoid dereference of null pointer in case of the failure of alloc.
> >> Signed-off-by: Jiasheng Jiang <jiasheng@...as.ac.cn>
> 
> >A blank line is always needed before the signed-off-by line.
> 
> >> ---
> >> Changelog:
> >> 
> >> v2 -> v3
> >> 
> >> *Change 1. Remove dev_err.
> >> *Change 2. Change the return type of pch_request_dma to int.
> >> *Change 3. Return -ENOMEM when dma_alloc_coherent() failed and 0 the
> >> others.
> >> *Change 4. Check return value of dma_alloc_coherent().
> >
> > I see v3 here, not v4.  Where is v4?
> >
> > And how did you test this change?
> >
> > thanks,
> >
> > greg k-h
> 
> Sorry, I just have v3, maybe that is my fault. But I don't know why you think there is v4.

You say "change 4".  Am I confused?

> And I have no idea about the "test this change"? Please give me more detail. 

Did you run the kernel before your change and then after your change to
ensure that the failure you saw before your change is now properly
fixed?

How did you test this?

thanks,

greg k-h