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Message-ID: <ec3a918a-df09-9245-318e-422f517ccf68@quicinc.com>
Date: Wed, 14 Aug 2024 11:05:02 +0530
From: Prashanth K <quic_prashk@...cinc.com>
To: Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
Faisal Hassan
<quic_faisalh@...cinc.com>
CC: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"linux-arm-msm@...r.kernel.org" <linux-arm-msm@...r.kernel.org>,
"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: Re: [PATCH] usb: dwc3: qcom: fix NULL pointer dereference on
dwc3_qcom_read_usb2_speed
On 14-08-24 05:47 am, Thinh Nguyen wrote:
> On Tue, Aug 13, 2024, Faisal Hassan wrote:
>> Null pointer dereference occurs when accessing 'hcd' to detect speed
>> from dwc3_qcom_suspend after the xhci-hcd is unbound.
>> To avoid this issue, ensure to check for NULL in dwc3_qcom_read_usb2_speed.
>>
>> echo xhci-hcd.0.auto > /sys/bus/platform/drivers/xhci-hcd/unbind
>> xhci_plat_remove() -> usb_put_hcd() -> hcd_release() -> kfree(hcd)
>>
>> Unable to handle kernel NULL pointer dereference at virtual address
>> 0000000000000060
>> Call trace:
>> dwc3_qcom_suspend.part.0+0x17c/0x2d0 [dwc3_qcom]
>> dwc3_qcom_runtime_suspend+0x2c/0x40 [dwc3_qcom]
>> pm_generic_runtime_suspend+0x30/0x44
>> __rpm_callback+0x4c/0x190
>> rpm_callback+0x6c/0x80
>> rpm_suspend+0x10c/0x620
>> pm_runtime_work+0xc8/0xe0
>> process_one_work+0x1e4/0x4f4
>> worker_thread+0x64/0x43c
>> kthread+0xec/0x100
>> ret_from_fork+0x10/0x20
>>
>> Fixes: c5f14abeb52b ("usb: dwc3: qcom: fix peripheral and OTG suspend")
>> Cc: stable@...r.kernel.org
>> Signed-off-by: Faisal Hassan <quic_faisalh@...cinc.com>
>> ---
>> drivers/usb/dwc3/dwc3-qcom.c | 4 +++-
>> 1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/usb/dwc3/dwc3-qcom.c b/drivers/usb/dwc3/dwc3-qcom.c
>> index 88fb6706a18d..0c7846478655 100644
>> --- a/drivers/usb/dwc3/dwc3-qcom.c
>> +++ b/drivers/usb/dwc3/dwc3-qcom.c
>> @@ -319,13 +319,15 @@ static bool dwc3_qcom_is_host(struct dwc3_qcom *qcom)
>> static enum usb_device_speed dwc3_qcom_read_usb2_speed(struct dwc3_qcom *qcom, int port_index)
>> {
>> struct dwc3 *dwc = platform_get_drvdata(qcom->dwc3);
>
> What if dwc is not available?
Thats unlikely, dwc3_qcom_suspend() -> dwc3_qcom_is_host() checks for
dwc, calls dwc3_qcom_read_usb2_speed() only if dwc is valid. But adding
an extra check shouldn't cause harm.
>
>> - struct usb_device *udev;
>> + struct usb_device __maybe_unused *udev;
>
> This is odd.... Is there a scenario where you don't want to set
> CONFIG_USB if dwc3_qcom is in use?
>
AFAIK this function is used to get the speeds of each ports, so that
wakeup interrupts (dp/dm/ss irqs) can be configured accordingly before
going to suspend, which is done during host mode only. So there
shouldn't be any scenarios where CONFIG_USB isnt set when this is called.
>> struct usb_hcd __maybe_unused *hcd;
>>
>> /*
>> * FIXME: Fix this layering violation.
>> */
>> hcd = platform_get_drvdata(dwc->xhci);
>> + if (!hcd)
>> + return USB_SPEED_UNKNOWN;
>>
>> #ifdef CONFIG_USB
>
> Perhaps this #ifdef shouldn't only be checking this. But that's for
> another patch >> udev = usb_hub_find_child(hcd->self.root_hub, port_index + 1);
>> --
>> 2.17.1
>>
>
> BR,
> Thinh
Thanks,
Prashanth K
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