linux-kernel - Re: [PATCH] of: overlay: fix memory leak of ovcs on error exit path

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Date:   Thu, 30 Nov 2017 12:54:17 +0000
From:   Colin Ian King <colin.king@...onical.com>
To:     Dan Carpenter <dan.carpenter@...cle.com>,
        Frank Rowand <frowand.list@...il.com>,
        Geert Uytterhoeven <geert+renesas@...der.be>
Cc:     Pantelis Antoniou <pantelis.antoniou@...sulko.com>,
        Rob Herring <robh+dt@...nel.org>, devicetree@...r.kernel.org,
        kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] of: overlay: fix memory leak of ovcs on error exit path

On 30/11/17 12:50, Dan Carpenter wrote:
> On Thu, Nov 30, 2017 at 07:14:45AM -0500, Frank Rowand wrote:
>> On 11/29/17 14:17, Colin King wrote:
>>> From: Colin Ian King <colin.king@...onical.com>
>>>
>>> Currently if the call to of_resolve_phandles fails then then ovcs
>>> is not kfree'd on the error exit path.  Rather than try and make
>>> the clean up exit path more convoluted, fix this by just kfree'ing
>>> ovcs at the point of error detection and exit via the same exit
>>> path.
>>>
>>> Detected by CoverityScan, CID#1462296 ("Resource Leak")
>>>
>>> Fixes: f948d6d8b792 ("of: overlay: avoid race condition between applying multiple overlays")
> 
> The Fixes tag is wrong.  It should be:
> 
> Fixes: bd80e2555c5c ("of: overlay: Fix cleanup order in of_overlay_apply()")

Good catch. I'll send a V2.

Colin

> 
>>> Signed-off-by: Colin Ian King <colin.king@...onical.com>
>>> ---
>>>  drivers/of/overlay.c | 4 +++-
>>>  1 file changed, 3 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
>>> index 53bc9e3f0b98..6c8efe7d8cbb 100644
>>> --- a/drivers/of/overlay.c
>>> +++ b/drivers/of/overlay.c
>>> @@ -708,8 +708,10 @@ int of_overlay_apply(struct device_node *tree, int *ovcs_id)
>>>  	of_overlay_mutex_lock();
>>>  
>>>  	ret = of_resolve_phandles(tree);
>>> -	if (ret)
>>> +	if (ret) {
>>> +		kfree(ovcs);
>>>  		goto err_overlay_unlock;
>>> +	}
>>>  
>>>  	mutex_lock(&of_mutex);
>>>  
>>>
>>
>> False coverity warning.  ovcs is freed in free_overlay_changeset().
> 
> You're looking at an older version of the code and Colin is looking at
> linux-next.
> 
> regards,
> dan carpenter
>