diff mbox series

[v2] usb: gadget: u_serial: check Null pointer in EP callback

Message ID PUZPR06MB62242AA2715789D100FA2E60D28D2@PUZPR06MB6224.apcprd06.prod.outlook.com
State Superseded
Headers show
Series [v2] usb: gadget: u_serial: check Null pointer in EP callback | expand

Commit Message

胡连勤 Aug. 20, 2024, 9:29 a.m. UTC
From: Lianqin Hu <hulianqin@vivo.com>

Added null pointer check to avoid system crash.

Unable to handle kernel NULL pointer dereference at
virtual address 00000000000001a8
pc : gs_read_complete+0x58/0x240
lr : usb_gadget_giveback_request+0x40/0x160
sp : ffffffc00f1539c0
x29: ffffffc00f1539c0 x28: ffffff8002a30000 x27: 0000000000000000
x26: ffffff8002a30000 x25: 0000000000000000 x24: ffffff8002a30000
x23: ffffff8002ff9a70 x22: ffffff898e7a7b00 x21: ffffff803c9af9d8
x20: ffffff898e7a7b00 x19: 00000000000001a8 x18: ffffffc0099fd098
x17: 0000000000001000 x16: 0000000080000000 x15: 0000000ac1200000
x14: 0000000000000003 x13: 000000000000d5e8 x12: 0000000355c314ac
x11: 0000000000000015 x10: 0000000000000012 x9 : 0000000000000008
x8 : 0000000000000000 x7 : 0000000000000000 x6 : ffffff887cd12000
x5 : 0000000000000002 x4 : ffffffc00f9b07f0 x3 : ffffffc00f1538d0
x2 : 0000000000000001 x1 : 0000000000000000 x0 : 00000000000001a8
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
el0t_64_sync_handler+0x88/0xec
el0t_64_sync+0x1b4/0x1b8
Code: aa1f03e1 aa1303e0 52800022 2a0103e8 (88e87e62)
---[ end trace 938847327a739172 ]---
Kernel panic - not syncing: Oops: Fatal exception

Signed-off-by: Lianqin Hu <hulianqin@vivo.com>
---
v2:
  - Optimize code comments
  - Delete log printing
---
 drivers/usb/gadget/function/u_serial.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

+   /* When port is NULL, return to avoid panic. */
+	if (!port)
+		return;
+
 	spin_lock(&port->port_lock);
 	list_add(&req->list, &port->write_pool);
 	port->write_started--;

Comments

胡连勤 Aug. 20, 2024, 10:52 a.m. UTC | #1
Hello linux community expert:

>> diff --git a/drivers/usb/gadget/function/u_serial.c 
>> b/drivers/usb/gadget/function/u_serial.c
>> index b394105e55d6..65637d53bf02
>> --- a/drivers/usb/gadget/function/u_serial.c
>> +++ b/drivers/usb/gadget/function/u_serial.c
>> @@ -454,6 +454,14 @@ static void gs_read_complete(struct usb_ep *ep, 
>> struct usb_request *req)  {
>>  	struct gs_port	*port = ep->driver_data;
>>  
>> +	/* When port is NULL, return to avoid panic. */
>> +	if (!port)
>> +		return;
>> +

>This doesn't protect the port from going to NULL right after the above the check. Since you mentioned gser_disconnect is making port to NULL, add the serial_port_lock to protect port (just like its done on gser_disconnect/suspend/resume). Something like this would do.
  OK, it is more reasonable to modify it as follows, I will modify it again.

>diff --git a/drivers/usb/gadget/function/u_serial.c
>b/drivers/usb/gadget/function/u_serial.c
>index f975dc03a190..a33f8cd871ac 100644
>--- a/drivers/usb/gadget/function/u_serial.c
>+++ b/drivers/usb/gadget/function/u_serial.c
>@@ -451,10 +451,21 @@ static void gs_rx_push(struct work_struct *work)

>static void gs_read_complete(struct usb_ep *ep, struct usb_request *req) {
>-       struct gs_port  *port = ep->driver_data;
>+       struct gs_port  *port;
>+       unsigned long   flags;
>+
>+       spin_lock_irqsave(&serial_port_lock, flags);
>+       port = ep->driver_data;
>+
>+       if (!port) {
>+               spin_unlock_irqrestore(&serial_port_lock, flags);
>+               return;
>+       }

>-       /* Queue all received data until the tty layer is ready for it. */
>       spin_lock(&port->port_lock);
>+       spin_unlock(&serial_port_lock);
>+
>+       /* Queue all received data until the tty layer is ready for it. 
>+ */
>       list_add_tail(&req->list, &port->read_queue);
>       schedule_delayed_work(&port->push, 0);
>       spin_unlock(&port->port_lock);
>
>>  	/* Queue all received data until the tty layer is ready for it. */
>>  	spin_lock(&port->port_lock);
>>  	list_add_tail(&req->list, &port->read_queue); @@ -465,6 +473,14 @@ 
>> static void gs_write_complete(struct usb_ep *ep, struct usb_request 
>> *req)  {
>>  	struct gs_port	*port = ep->driver_data;
>>  
>> +   /* When port is NULL, return to avoid panic. */
>> +	if (!port)
>> +		return;
>> +
>>  	spin_lock(&port->port_lock);
>>  	list_add(&req->list, &port->write_pool);
>>  	port->write_started--;
>Same here also

Thanks
Greg KH Aug. 20, 2024, 11:51 a.m. UTC | #2
On Tue, Aug 20, 2024 at 09:29:05AM +0000, 胡连勤 wrote:
> From: Lianqin Hu <hulianqin@vivo.com>
> 
> Added null pointer check to avoid system crash.
> 
> Unable to handle kernel NULL pointer dereference at
> virtual address 00000000000001a8
> pc : gs_read_complete+0x58/0x240
> lr : usb_gadget_giveback_request+0x40/0x160
> sp : ffffffc00f1539c0
> x29: ffffffc00f1539c0 x28: ffffff8002a30000 x27: 0000000000000000
> x26: ffffff8002a30000 x25: 0000000000000000 x24: ffffff8002a30000
> x23: ffffff8002ff9a70 x22: ffffff898e7a7b00 x21: ffffff803c9af9d8
> x20: ffffff898e7a7b00 x19: 00000000000001a8 x18: ffffffc0099fd098
> x17: 0000000000001000 x16: 0000000080000000 x15: 0000000ac1200000
> x14: 0000000000000003 x13: 000000000000d5e8 x12: 0000000355c314ac
> x11: 0000000000000015 x10: 0000000000000012 x9 : 0000000000000008
> x8 : 0000000000000000 x7 : 0000000000000000 x6 : ffffff887cd12000
> x5 : 0000000000000002 x4 : ffffffc00f9b07f0 x3 : ffffffc00f1538d0
> x2 : 0000000000000001 x1 : 0000000000000000 x0 : 00000000000001a8
> 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
> el0t_64_sync_handler+0x88/0xec
> el0t_64_sync+0x1b4/0x1b8
> Code: aa1f03e1 aa1303e0 52800022 2a0103e8 (88e87e62)
> ---[ end trace 938847327a739172 ]---
> Kernel panic - not syncing: Oops: Fatal exception
> 
> Signed-off-by: Lianqin Hu <hulianqin@vivo.com>
> ---
> v2:
>   - Optimize code comments
>   - Delete log printing
> ---
>  drivers/usb/gadget/function/u_serial.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)

Any specific reason you ignored my previous review comments?
diff mbox series

Patch

diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c
index b394105e55d6..65637d53bf02
--- a/drivers/usb/gadget/function/u_serial.c
+++ b/drivers/usb/gadget/function/u_serial.c
@@ -454,6 +454,14 @@  static void gs_read_complete(struct usb_ep *ep, struct usb_request *req)
 {
 	struct gs_port	*port = ep->driver_data;
 
+	/* When port is NULL, return to avoid panic. */
+	if (!port)
+		return;
+
 	/* Queue all received data until the tty layer is ready for it. */
 	spin_lock(&port->port_lock);
 	list_add_tail(&req->list, &port->read_queue);
@@ -465,6 +473,14 @@  static void gs_write_complete(struct usb_ep *ep, struct usb_request *req)
 {
 	struct gs_port	*port = ep->driver_data;