netdev - Re: [PATCH] net: pch_gbe: Fix memory leaks

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Message-Id: <20190815.135111.1048854967874803531.davem@davemloft.net>
Date:   Thu, 15 Aug 2019 13:51:11 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     wenwen@...uga.edu
Cc:     rfontana@...hat.com, allison@...utok.net, alexios.zavras@...el.com,
        gregkh@...uxfoundation.org, tglx@...utronix.de,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: pch_gbe: Fix memory leaks

From: Wenwen Wang <wenwen@...uga.edu>
Date: Thu, 15 Aug 2019 16:46:05 -0400

> On Thu, Aug 15, 2019 at 4:42 PM David Miller <davem@...emloft.net> wrote:
>>
>> From: Wenwen Wang <wenwen@...uga.edu>
>> Date: Thu, 15 Aug 2019 16:03:39 -0400
>>
>> > On Thu, Aug 15, 2019 at 3:34 PM David Miller <davem@...emloft.net> wrote:
>> >>
>> >> From: Wenwen Wang <wenwen@...uga.edu>
>> >> Date: Tue, 13 Aug 2019 20:33:45 -0500
>> >>
>> >> > In pch_gbe_set_ringparam(), if netif_running() returns false, 'tx_old' and
>> >> > 'rx_old' are not deallocated, leading to memory leaks. To fix this issue,
>> >> > move the free statements after the if branch.
>> >> >
>> >> > Signed-off-by: Wenwen Wang <wenwen@...uga.edu>
>> >>
>> >> Why would they be "deallocated"?  They are still assigned to
>> >> adapter->tx_ring and adapter->rx_ring.
>> >
>> > 'adapter->tx_ring' and 'adapter->rx_ring' has been covered by newly
>> > allocated 'txdr' and 'rxdr' respectively before this if statement.
>>
>> That only happens inside of the if() statement, that's why rx_old and
>> tx_old are only freed in that code path.
> 
> That happens not only inside of the if statement, but also before the
> if statement, just after 'txdr' and 'rxdr' are allocated.

Then the assignments inside of the if() statement are redundant.

Something doesn't add up here, please make the code consistent.