linux-kernel - Re: [PATCH] usb: dwc3: Fix dereferencing of null dwc->usb

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Message-ID: <b93ff323-e03c-10b3-c38d-921bc6b2edc0@canonical.com>
Date:   Wed, 3 Mar 2021 22:47:22 +0000
From:   Colin Ian King <colin.king@...onical.com>
To:     Heiko Thiery <heiko.thiery@...il.com>, raychi@...gle.com
Cc:     balbi@...nel.org, gregkh@...uxfoundation.org,
        kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-usb@...r.kernel.org
Subject: Re: [PATCH] usb: dwc3: Fix dereferencing of null dwc->usb_psy

On 03/03/2021 21:29, Heiko Thiery wrote:
> Hi all,
> 
>> On Wed, Mar 3, 2021 at 6:00 PM Colin King <colin.king@...onical.com> wrote:
>>>
>>> From: Colin Ian King <colin.king@...onical.com>
>>>
>>> Currently the null check logic on dwc->usb_psy is inverted as it allows
>>> calls to power_supply_put with a null dwc->usb_psy causing a null
>>> pointer dereference. Fix this by removing the ! operator.
>>>
>>> Addresses-Coverity: ("Dereference after null check")
>>> Fixes: 59fa3def35de ("usb: dwc3: add a power supply for current control")
>>
>> Acked-by: Ray Chi <raychi@...gle.com>
>>
>>> Signed-off-by: Colin Ian King <colin.king@...onical.com>
> 
> Tested-by: Heiko Thiery <heiko.thiery@...il.com>

Thanks for testing. Much appreciated.

Colin
> 
>>> ---
>>>  drivers/usb/dwc3/core.c | 4 ++--
>>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
>>> index d15f065849cd..94fdbe502ce9 100644
>>> --- a/drivers/usb/dwc3/core.c
>>> +++ b/drivers/usb/dwc3/core.c
>>> @@ -1628,7 +1628,7 @@ static int dwc3_probe(struct platform_device *pdev)
>>>  assert_reset:
>>>         reset_control_assert(dwc->reset);
>>>
>>> -       if (!dwc->usb_psy)
>>> +       if (dwc->usb_psy)
>>>                 power_supply_put(dwc->usb_psy);
>>>
>>>         return ret;
>>> @@ -1653,7 +1653,7 @@ static int dwc3_remove(struct platform_device *pdev)
>>>         dwc3_free_event_buffers(dwc);
>>>         dwc3_free_scratch_buffers(dwc);
>>>
>>> -       if (!dwc->usb_psy)
>>> +       if (dwc->usb_psy)
>>>                 power_supply_put(dwc->usb_psy);
>>>
>>>         return 0;
>>> --
>>> 2.30.0
>>>
> 
> Thank you.
>