linux-kernel - Re: [PATCH] iio: gts-helper: Fix memory leaks for i = 1 error path

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Message-ID: <ec2e2c43-e369-e932-0344-9bbbfea735b5@huawei.com>
Date: Tue, 15 Oct 2024 17:10:38 +0800
From: Jinjie Ruan <ruanjinjie@...wei.com>
To: Matti Vaittinen <mazziesaccount@...il.com>, <jic23@...nel.org>,
	<lars@...afoo.de>, <linux-iio@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] iio: gts-helper: Fix memory leaks for i = 1 error path



On 2024/10/15 17:03, Matti Vaittinen wrote:
> Thanks a lot Jinjie. I appreciate your fixes!
> 
> On 14/10/2024 04:31, Jinjie Ruan wrote:
>> If i = 1, and per_time_scales[i] or per_time_gains[i] kcalloc fails in
>> iio_gts_build_avail_scale_table(), the err_free_out will fail to enter
>> kfree for loop because i-- is 0, and all the per_time_scales[0] and
>> per_time_gains[0] will not be freed, which will cause memory leaks.
> 
> I guess the loop never frees the memory pointed by the first pointer in
> these arrays. I mean, the freeing is not working as it should even if
> the 'i' was something else but 1.

Yes, the title is not very clear. In fact, all the per_time_scales[0] or
per_time_scales[0] in the function error path are not released.

> 
>>
>> Fix it by checking if i >= 0.
> 
> The fix seems good to me. So, with a tiny change in commit message:
> 
> Reviewed-by: Matti Vaittinen <mazziesaccount@...il.com>
> 
>>
>> Cc: stable@...r.kernel.org
>> Fixes: 38416c28e168 ("iio: light: Add gain-time-scale helpers")
>> Signed-off-by: Jinjie Ruan <ruanjinjie@...wei.com>
>> ---
>>   drivers/iio/industrialio-gts-helper.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/iio/industrialio-gts-helper.c
>> b/drivers/iio/industrialio-gts-helper.c
>> index 7326c7949244..5f131bc1a01e 100644
>> --- a/drivers/iio/industrialio-gts-helper.c
>> +++ b/drivers/iio/industrialio-gts-helper.c
>> @@ -315,7 +315,7 @@ static int iio_gts_build_avail_scale_table(struct
>> iio_gts *gts)
>>       return 0;
>>     err_free_out:
>> -    for (i--; i; i--) {
>> +    for (i--; i >= 0; i--) {
>>           kfree(per_time_scales[i]);
>>           kfree(per_time_gains[i]);
>>       }
>