linux-kernel - Re: [PATCH v2] thunderbolt: Fix to check return value of ida_simple

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Date:   Thu, 21 Mar 2019 02:09:41 +0530
From:   Mukesh Ojha <mojha@...eaurora.org>
To:     Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Aditya Pakki <pakki001@....edu>
Cc:     kjlu@....edu, Andreas Noever <andreas.noever@...il.com>,
        Michael Jamet <michael.jamet@...el.com>,
        Yehezkel Bernat <YehezkelShB@...il.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] thunderbolt: Fix to check return value of
 ida_simple_get


On 3/20/2019 9:59 PM, Mika Westerberg wrote:
> On Wed, Mar 20, 2019 at 11:24:45AM -0500, Aditya Pakki wrote:
>> In enumerate_services, ida_simple_get on failure can return an error and
>> leaks memory during device_register failure. The patch ensures that
>> the dev_set_name is set on non failure cases, and releases memory in
>> case of failure.
>>
>> Signed-off-by: Aditya Pakki <pakki001@....edu>
>>
>> ---
>> v1: Missed cleanup of svc in case of allocation failure and
>> device_register failure.
>> ---
>>   drivers/thunderbolt/xdomain.c | 9 ++++++++-
>>   1 file changed, 8 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/thunderbolt/xdomain.c b/drivers/thunderbolt/xdomain.c
>> index e27dd8beb94b..eb08275185bf 100644
>> --- a/drivers/thunderbolt/xdomain.c
>> +++ b/drivers/thunderbolt/xdomain.c
>> @@ -740,6 +740,7 @@ static void enumerate_services(struct tb_xdomain *xd)
>>   	struct tb_service *svc;
>>   	struct tb_property *p;
>>   	struct device *dev;
>> +	int id;
>>   
>>   	/*
>>   	 * First remove all services that are not available anymore in
>> @@ -768,7 +769,12 @@ static void enumerate_services(struct tb_xdomain *xd)
>>   			break;
>>   		}
>>   
>> -		svc->id = ida_simple_get(&xd->service_ids, 0, 0, GFP_KERNEL);
>> +		id = ida_simple_get(&xd->service_ids, 0, 0, GFP_KERNEL);
>> +		if (id < 0) {
>> +			kfree(svc);
>> +			break;
>> +		}
>> +		svc->id = id;
>>   		svc->dev.bus = &tb_bus_type;
>>   		svc->dev.type = &tb_service_type;
>>   		svc->dev.parent = &xd->dev;
>> @@ -776,6 +782,7 @@ static void enumerate_services(struct tb_xdomain *xd)
>>   
>>   		if (device_register(&svc->dev)) {
>>   			put_device(&svc->dev);
>> +			kfree(svc);
> You can't do this after device_register() is called. The put_device()
> above is sufficient.


If  device_register fails, how would svc gets freed? we need  to kfree 
svc here as well.

Thanks,
Mukesh