[PATCH v2] usb: gadget: u_serial: Disable ep before setting port to null to fix the crash caused by port being null

[PATCH v2] usb: gadget: u_serial: Disable ep before setting port to null to fix the crash caused by port being null

[胡连勤]

From: Lianqin Hu <hulianqin@vivo.com>

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.

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

Fixes: c1dca562be8a ("usb gadget: split out serial core")
Cc: stable@vger.kernel.org

Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Lianqin Hu <hulianqin@vivo.com>

v2:
 - Remove some address information from patch descriptions
 - Link to v1: https://lore.kernel.org/all/TYUPR06MB621763AB815989161F4033AFD2762@TYUPR06MB6217.apcprd06.prod.outlook.com/
 - Link to suggestions: https://lore.kernel.org/all/TYUPR06MB6217DE28012FFEC5E808DD64D2962@TYUPR06MB6217.apcprd06.prod.outlook.com/

 drivers/usb/gadget/function/u_serial.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c
index 53d9fc41acc5..bc143a86c2dd 100644
--- a/drivers/usb/gadget/function/u_serial.c
+++ b/drivers/usb/gadget/function/u_serial.c
@@ -1420,6 +1420,10 @@ void gserial_disconnect(struct gserial *gser)
 	/* REVISIT as above: how best to track this? */
 	port->port_line_coding = gser->port_line_coding;
 
+	/* disable endpoints, aborting down any active I/O */
+	usb_ep_disable(gser->out);
+	usb_ep_disable(gser->in);
+
 	port->port_usb = NULL;
 	gser->ioport = NULL;
 	if (port->port.count > 0) {
@@ -1431,10 +1435,6 @@ void gserial_disconnect(struct gserial *gser)
 	spin_unlock(&port->port_lock);
 	spin_unlock_irqrestore(&serial_port_lock, flags);
 
-	/* disable endpoints, aborting down any active I/O */
-	usb_ep_disable(gser->out);
-	usb_ep_disable(gser->in);
-
 	/* finally, free any unused/unusable I/O buffers */
 	spin_lock_irqsave(&port->port_lock, flags);
 	if (port->port.count == 0)
-- 
2.39.0

Re: [PATCH v2] usb: gadget: u_serial: Disable ep before setting port to null to fix the crash caused by port being null

[gregkh]

On Mon, Dec 16, 2024 at 12:31:45PM +0000, 胡连勤 wrote:
> From: Lianqin Hu <hulianqin@vivo.com>
> 
> 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.
> 
> 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
> 
> Fixes: c1dca562be8a ("usb gadget: split out serial core")
> Cc: stable@vger.kernel.org
> 
> Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Signed-off-by: Lianqin Hu <hulianqin@vivo.com>
> 
> v2:
>  - Remove some address information from patch descriptions
>  - Link to v1: https://lore.kernel.org/all/TYUPR06MB621763AB815989161F4033AFD2762@TYUPR06MB6217.apcprd06.prod.outlook.com/
>  - Link to suggestions: https://lore.kernel.org/all/TYUPR06MB6217DE28012FFEC5E808DD64D2962@TYUPR06MB6217.apcprd06.prod.outlook.com/

The "v2:" needs to go below the --- line, what happened to that?

And no need to have a blank line after the cc: stable, right?  Did you
run checkpatch.pl on this?

thanks,

greg k-h

答复: [PATCH v2] usb: gadget: u_serial: Disable ep before setting port to null to fix the crash caused by port being null

[胡连勤]

Hello  Linux kernel expert:

> > From: Lianqin Hu <hulianqin@vivo.com>
> >
> > 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.
> >
> > 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
> >
> > Fixes: c1dca562be8a ("usb gadget: split out serial core")
> > Cc: stable@vger.kernel.org
> >
> > Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > Signed-off-by: Lianqin Hu <hulianqin@vivo.com>
> >
> > v2:
> >  - Remove some address information from patch descriptions
> >  - Link to v1:
> > https://apc01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore
> > .kernel.org%2Fall%2FTYUPR06MB621763AB815989161F4033AFD2762%40TY
> UPR06MB
> >  - Link to suggestions:
> > https://apc01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore
> > .kernel.org%2Fall%2FTYUPR06MB6217DE28012FFEC5E808DD64D2962%40TY
> UPR06MB
> 
> The "v2:" needs to go below the --- line, what happened to that?
   OK, I'll modify it.

> And no need to have a blank line after the cc: stable, right?  Did you run
> checkpatch.pl on this?
Sorry, I didn't check it carefully enough. I will modify it and send a new patch.

Run checkpatch.pl before sending the patch:
root@vivo-600-G6:~/linux_kernel/linux# ./scripts/checkpatch.pl 0001-usb-gadget-u_serial-Disable-ep-before-setting-port-t.patch 
total: 0 errors, 0 warnings, 20 lines checked

Thanks