linux-kernel - Re: [PATCH v2] usb: gadget: Set self-powered based on MaxPower and bmAttributes

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Message-ID: <53f8a9cd-c30c-47fe-b189-c632a093dc66@quicinc.com>
Date: Mon, 24 Feb 2025 09:47:02 +0530
From: Prashanth K <quic_prashk@...cinc.com>
To: Kees Bakker <kees@...erbout.nl>,
        Prashanth K
	<prashanth.k@....qualcomm.com>
CC: <linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <stable@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
        Peter Korsgaard
	<peter@...sgaard.com>,
        Sabyrzhan Tasbolatov <snovitoll@...il.com>
Subject: Re: [PATCH v2] usb: gadget: Set self-powered based on MaxPower and
 bmAttributes



On 22-02-25 12:56 am, Kees Bakker wrote:
> Op 17-02-2025 om 13:03 schreef Prashanth K:
>> Currently the USB gadget will be set as bus-powered based solely
>> on whether its bMaxPower is greater than 100mA, but this may miss
>> devices that may legitimately draw less than 100mA but still want
>> to report as bus-powered. Similarly during suspend & resume, USB
>> gadget is incorrectly marked as bus/self powered without checking
>> the bmAttributes field. Fix these by configuring the USB gadget
>> as self or bus powered based on bmAttributes, and explicitly set
>> it as bus-powered if it draws more than 100mA.
>>
>> Cc: stable@...r.kernel.org
>> Fixes: 5e5caf4fa8d3 ("usb: gadget: composite: Inform controller driver
>> of self-powered")
>> Signed-off-by: Prashanth K <prashanth.k@....qualcomm.com>
>> ---
>> Changes in v2:
>> - Didn't change anything from RFC.
>> - Link to RFC: https://lore.kernel.org/all/20250204105908.2255686-1-
>> prashanth.k@....qualcomm.com/
>>
>>   drivers/usb/gadget/composite.c | 16 +++++++++++-----
>>   1 file changed, 11 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/
>> composite.c
>> index bdda8c74602d..1fb28bbf6c45 100644
>> --- a/drivers/usb/gadget/composite.c
>> +++ b/drivers/usb/gadget/composite.c
>> @@ -1050,10 +1050,11 @@ static int set_config(struct usb_composite_dev
>> *cdev,
>>       else
>>           usb_gadget_set_remote_wakeup(gadget, 0);
>>   done:
>> -    if (power <= USB_SELF_POWER_VBUS_MAX_DRAW)
>> -        usb_gadget_set_selfpowered(gadget);
>> -    else
>> +    if (power > USB_SELF_POWER_VBUS_MAX_DRAW ||
>> +        !(c->bmAttributes & USB_CONFIG_ATT_SELFPOWER))
> Please check this change again. From line 983-884 there is a `goto done`.
> in case `c` is NULL. So, there will be a potential NULL pointer dereference
> with your change.

Yea good catch, sorry for missing the corner case. Ill send another patch.

Regards,
Prashanth K