linux-kernel - Re: [PATCH 4.19] dmaengine: at

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Date:   Tue, 5 Jan 2021 08:03:20 +0000
From:   <Tudor.Ambarus@...rochip.com>
To:     <gregkh@...uxfoundation.org>
CC:     <pavel@....cz>, <linux-kernel@...r.kernel.org>,
        <dmaengine@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <dan.j.williams@...el.com>,
        <vkoul@...nel.org>, <Ludovic.Desroches@...rochip.com>,
        <stable@...r.kernel.org>
Subject: Re: [PATCH 4.19] dmaengine: at_hdmac: Fix memory leak

On 1/4/21 1:02 PM, Greg KH wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> On Wed, Sep 23, 2020 at 08:19:18AM +0000, Tudor.Ambarus@...rochip.com wrote:
>> On 9/23/20 11:13 AM, Tudor.Ambarus@...rochip.com wrote:
>>> Hi, Pavel,
>>>
>>> On 9/20/20 11:28 AM, Pavel Machek wrote:
>>>> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
>>>>
>>>> This fixes memory leak in at_hdmac. Mainline does not have the same
>>>> problem.
>>>>
>>>> Signed-off-by: Pavel Machek (CIP) <pavel@...x.de>
>>>>
>>>> diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
>>>> index 86427f6ba78c..0847b2055857 100644
>>>> --- a/drivers/dma/at_hdmac.c
>>>> +++ b/drivers/dma/at_hdmac.c
>>>> @@ -1714,8 +1714,10 @@ static struct dma_chan *at_dma_xlate(struct of_phandle_args *dma_spec,
>>>>         atslave->dma_dev = &dmac_pdev->dev;
>>>>
>>>>         chan = dma_request_channel(mask, at_dma_filter, atslave);
>>>> -       if (!chan)
>>>> +       if (!chan) {
>>>> +               kfree(atslave);
>>>>                 return NULL;
>>>> +       }
>>>
>>> Thanks for submitting this to stable. While the fix is good, you can instead
>>> cherry-pick the commit that hit upstream. In order to do that cleanly on top
>>> of v4.19.145, you have to pick two other fixes:
>>>
>>> commit a6e7f19c9100 ("dmaengine: at_hdmac: Substitute kzalloc with kmalloc")
>>> commit 3832b78b3ec2 ("dmaengine: at_hdmac: add missing put_device() call in at_dma_xlate()")>>> commit a6e7f19c9100 ("dmaengine: at_hdmac: Substitute kzalloc with kmalloc")
>>
>> this last commit should have been
>> commit e097eb7473d9 ("dmaengine: at_hdmac: add missing kfree() call in at_dma_xlate()")
>>
>> bad copy and paste :)
> 
> So are all 3 of those needed on both 5.4.y and 4.19.y to resolve this
> issue?
> 

Yes. I've just cherry-picked all three commits on both v5.4.86 and v4.19.164,
everything looks ok. I also compiled using sama5_defconfig, all good.

The order in which they should be taken is 1/ a6e7f19c9100, then 2/ 3832b78b3ec2,
and 3/ e097eb7473d9.

Cheers,
ta