Re: [PATCH 4.19] dmaengine: at_hdmac: Fix memory leak

From: Tudor.Ambarus
Date: Wed Sep 23 2020 - 04:19:25 EST


On 9/23/20 11:13 AM, Tudor.Ambarus@xxxxxxxxxxxxx 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@xxxxxxx>
>>
>> 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 :)

>
> There are also some locking/deadlock fixes in mainline for this driver,
> depending on the time you can allocate for this, the list of patches can increase.
> I should have Cc'ed stable@xxxxxxxxxxxxxxx in the first place, my bad.
>
> Also it may worth to read the rules for submitting to stable at:
> https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
>
> Cheers,
> ta
>
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