linux-kernel - Re: 答复: [PATCH v3] usb: gadget: u_serial: Disable ep before setting port to null to fix the crash caused by port being null

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Message-ID: <a39cee8d-bf79-4fa3-96fd-e414af8c9f74@quicinc.com>
Date: Thu, 26 Dec 2024 10:29:59 +0530
From: Prashanth K <quic_prashk@...cinc.com>
To: 胡连勤 <hulianqin@...o.com>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "mwalle@...nel.org" <mwalle@...nel.org>,
        "quic_jjohnson@...cinc.com"
	<quic_jjohnson@...cinc.com>,
        David Brownell <dbrownell@...rs.sourceforge.net>
CC: "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        opensource.kernel <opensource.kernel@...o.com>
Subject: Re: 答复: [PATCH v3] usb: gadget: u_serial: Disable ep before setting port to null to fix the crash caused by port being null



On 25-12-24 12:33 pm, 胡连勤 wrote:
> Hello  Prashanth K:
> 
>>> Considering that in some extreme cases, when performing the unbinding
>>> operation, gserial_disconnect has cleared gser->ioport, which triggers
>>> gadget reconfiguration, and then calls gs_read_complete, resulting in
>>> access to a null pointer. Therefore, ep is disabled before
>>> gserial_disconnect sets port to null to prevent this from happening.
>>
>> gs_read_complete() gets port from ep->driver_data, and it shouldn't get
>> affected if gser->ioport is null as long as port[port_num].port is valid. Am I
>> missing something here?
> 
> This description is not very appropriate, thank you very much for your suggestion, I will modify it.

Seems like this patch has already accepted applied to Gregs tree. So I
think its fine for now, just update new description here.

> 
>>>
>>> Call trace:
>>>  gs_read_complete+0x58/0x240
>>>  usb_gadget_giveback_request+0x40/0x160
>>>  dwc3_remove_requests+0x170/0x484
>>>  dwc3_ep0_out_start+0xb0/0x1d4
>>>  __dwc3_gadget_start+0x25c/0x720
>>>  kretprobe_trampoline.cfi_jt+0x0/0x8
>>>  kretprobe_trampoline.cfi_jt+0x0/0x8
>>>  udc_bind_to_driver+0x1d8/0x300
>>>  usb_gadget_probe_driver+0xa8/0x1dc
>>>  gadget_dev_desc_UDC_store+0x13c/0x188
>>>  configfs_write_iter+0x160/0x1f4
>>>  vfs_write+0x2d0/0x40c
>>>  ksys_write+0x7c/0xf0
>>>  __arm64_sys_write+0x20/0x30
>>>  invoke_syscall+0x60/0x150
>>>  el0_svc_common+0x8c/0xf8
>>>  do_el0_svc+0x28/0xa0
>>>  el0_svc+0x24/0x84
>>>
> 
> Thanks

Regards,
Prashanth K