[Devel] [PATCH 1/1] Drivers: md: ploop - Do not leak a page on allocation failure

[Vasily Averin]

On 7/20/22 21:02, Alexander Atanasov wrote:
> Hi,
> 
> On 20/07/2022 20:57, Vasily Averin wrote:
> 
>> Hi Alexander!
>>
>> On 7/20/22 14:05, Alexander Atanasov wrote:
>>> Fix off-by-one error - tries to free the failed allocation and
>>> it leaks the first successful
>> Could you please elaborate? I do not see the difference in behavior.
>>
>> if we have failed on 2nd allocation
>> we have i = 1
>> io_vec[0] was set
>> io_vec[1] was failed
>> we jump to err: label
>> doing i-- end call put_page for io_vec[0]
>> 2nd turn fails.
>> So looks like all works correctly.
>> With your patch situation is not changed.
>>
>> Am I missed something perhaps?
> 
> 
> No, of course you are not. My bad i overlooked it. Please, ignore.

Do not worry, you are fine!

>>
>> Thank you,
>>     Vasily Averin
>>
>>> Signed-off-by: Alexander Atanasov <alexander.atanasov at virtuozzo.com>
>>> ---
>>>   drivers/md/dm-ploop-cmd.c | 2 +-
>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/md/dm-ploop-cmd.c b/drivers/md/dm-ploop-cmd.c
>>> index 429a03cce392..e4ea738828bc 100644
>>> --- a/drivers/md/dm-ploop-cmd.c
>>> +++ b/drivers/md/dm-ploop-cmd.c
>>> @@ -489,7 +489,7 @@ struct pio *alloc_pio_with_pages(struct ploop *ploop)
>>>         return pio;
>>>   err:
>>> -    while (i-- > 0)
>>> +    while (--i >= 0)
>>>           put_page(pio->bi_io_vec[i].bv_page);
>>>       kfree(pio);
>>>       return NULL;
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>