linux-kernel - Re: [PATCH] nfc: fix memory leak of se_io context in nfc_genl_se

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Message-ID: <7e9ffa10-d6e8-48b5-e832-cf77ac1a8802@linaro.org>
Date:   Tue, 28 Feb 2023 11:14:03 +0100
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Fedor Pchelkin <pchelkin@...ras.ru>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Guenter Roeck <groeck@...gle.com>,
        Martin Faltesek <mfaltesek@...gle.com>,
        Duoming Zhou <duoming@....edu.cn>,
        Samuel Ortiz <sameo@...ux.intel.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Alexey Khoroshilov <khoroshilov@...ras.ru>,
        lvc-project@...uxtesting.org,
        syzbot+df64c0a2e8d68e78a4fa@...kaller.appspotmail.com
Subject: Re: [PATCH] nfc: fix memory leak of se_io context in nfc_genl_se_io

On 27/02/2023 16:05, Fedor Pchelkin wrote:
>>> Fixes: 5ce3f32b5264 ("NFC: netlink: SE API implementation")
>>> Reported-by: syzbot+df64c0a2e8d68e78a4fa@...kaller.appspotmail.com
>>> Signed-off-by: Fedor Pchelkin <pchelkin@...ras.ru>
>>> Signed-off-by: Alexey Khoroshilov <khoroshilov@...ras.ru>
>>
>> SoB order is a bit odd. Who is the author?
>>
> 
> The author is me (Fedor). I thought the authorship is expressed with the
> first Signed-off-by line, isn't it?

Yes and since you are sending it, then what is Alexey's Sob for? The
tags are in order...

> 
>>> ---
>>>  drivers/nfc/st-nci/se.c   | 6 ++++++
>>>  drivers/nfc/st21nfca/se.c | 6 ++++++
>>>  net/nfc/netlink.c         | 4 ++++
>>>  3 files changed, 16 insertions(+)
>>>
>>> diff --git a/drivers/nfc/st-nci/se.c b/drivers/nfc/st-nci/se.c
>>> index ec87dd21e054..b2f1ced8e6dd 100644
>>> --- a/drivers/nfc/st-nci/se.c
>>> +++ b/drivers/nfc/st-nci/se.c
>>> @@ -672,6 +672,12 @@ int st_nci_se_io(struct nci_dev *ndev, u32 se_idx,
>>>  					ST_NCI_EVT_TRANSMIT_DATA, apdu,
>>>  					apdu_length)
>> nci_hci_send_event() should also free it in its error paths.
>> nci_data_exchange_complete() as well? Who eventually frees it? These
>> might be separate patches.
>>
>>
> 
> nci_hci_send_event(), as I can see, should not free the callback context.
> I should have probably better explained that in the commit info (will
> include this in the patch v2), but the main thing is: nfc_se_io() is
> called with se_io_cb callback function as an argument and that callback is 
> the exact place where an allocated se_io_ctx context should be freed. And
> it is actually freed there unless some error path happens that leads the

Exactly, so why nci_hci_send_event() error path should not free it?

> timer which triggers this se_io_cb callback not to be charged at all.
> 


Best regards,
Krzysztof