2019-11-03 02:46:55

by hui yang

Subject: [PATCH 2/2] USB(u_serial.c): it has a NULL point

From: YangHui <[email protected]>

Unable to handle kernel NULL pointer dereference at virtual address 000002a0
Kernel BUG at tty_wakeup+0x18/0x8c
[<0000000095135e9d>] tty_wakeup+0x18/0x8c
[<00000000c35f19e4>] gs_start_io+0xc8/0x158
[<00000000b11b184e>] gserial_connect+0xd0/0x174
[<00000000642201de>] acm_set_alt+0x70/0x180
[<00000000a9d38e8b>] composite_setup+0x1848/0x1a7c
[<0000000072c88781>] android_setup+0x1ec/0x1f4
[<000000004c0127a5>] msm_udc_irq+0x8d0/0xc0c
[<00000000f8bb9acf>] __handle_irq_event_percpu+0x74/0x294
[<00000000afd57256>] handle_irq_event+0x60/0xc8
[<0000000076719b24>] handle_fasteoi_irq+0xc8/0x1c4
[<00000000421f3d87>] generic_handle_irq+0x34/0x4c
[<00000000b2f2d343>] __handle_domain_irq+0x6c/0xbc
[<00000000c74325e8>] gic_handle_irq+0x6c/0xe0
yes,we can see the port->port.tty==NULL, so system crashed

Signed-off-by: YangHui <[email protected]>
---
drivers/usb/gadget/function/u_serial.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c
index 65f634e..a1c2ac2 100644
--- a/drivers/usb/gadget/function/u_serial.c
+++ b/drivers/usb/gadget/function/u_serial.c
@@ -562,6 +562,8 @@ static int gs_start_io(struct gs_port *port)

/* unblock any pending writes into our circular buffer */
if (started) {
+ if (port->port.tty == NULL)
+ return -EIO;
tty_wakeup(port->port.tty);
} else {
gs_free_requests(ep, head, &port->read_allocated);
--
2.7.4

2019-11-03 12:43:05

by Greg Kroah-Hartman

Subject: Re: [PATCH 2/2] USB(u_serial.c): it has a NULL point

On Sun, Nov 03, 2019 at 10:44:04AM +0800, hui yang wrote:
> From: YangHui <[email protected]>
>
> Unable to handle kernel NULL pointer dereference at virtual address 000002a0
> Kernel BUG at tty_wakeup+0x18/0x8c
> [<0000000095135e9d>] tty_wakeup+0x18/0x8c
> [<00000000c35f19e4>] gs_start_io+0xc8/0x158
> [<00000000b11b184e>] gserial_connect+0xd0/0x174
> [<00000000642201de>] acm_set_alt+0x70/0x180
> [<00000000a9d38e8b>] composite_setup+0x1848/0x1a7c
> [<0000000072c88781>] android_setup+0x1ec/0x1f4
> [<000000004c0127a5>] msm_udc_irq+0x8d0/0xc0c
> [<00000000f8bb9acf>] __handle_irq_event_percpu+0x74/0x294
> [<00000000afd57256>] handle_irq_event+0x60/0xc8
> [<0000000076719b24>] handle_fasteoi_irq+0xc8/0x1c4
> [<00000000421f3d87>] generic_handle_irq+0x34/0x4c
> [<00000000b2f2d343>] __handle_domain_irq+0x6c/0xbc
> [<00000000c74325e8>] gic_handle_irq+0x6c/0xe0
> yes,we can see the port->port.tty==NULL, so system crashed
>
> Signed-off-by: YangHui <[email protected]>
> ---
> drivers/usb/gadget/function/u_serial.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c
> index 65f634e..a1c2ac2 100644
> --- a/drivers/usb/gadget/function/u_serial.c
> +++ b/drivers/usb/gadget/function/u_serial.c
> @@ -562,6 +562,8 @@ static int gs_start_io(struct gs_port *port)
>
> /* unblock any pending writes into our circular buffer */
> if (started) {
> + if (port->port.tty == NULL)
> + return -EIO;

How can this happen? Shouldn't this be handled earlier?

If not, can you document this how this can be true and what should be
done about it?

thanks,

greg k-h

2019-11-03 14:19:20

by Greg Kroah-Hartman

Subject: Re: [PATCH 2/2] USB(u_serial.c): it has a NULL point

On Sun, Nov 03, 2019 at 10:01:11PM +0800, [email protected] wrote:

html email is deleted by the list :(

2019-11-09 07:50:24

by hui yang

Subject: Re: [PATCH 2/2] USB(u_serial.c): it has a NULL point

I'm sorry for my fault . Now I send to everyone .

When we use USB to transmit data
with PC, the phone will crashed Low probability .
We found port->port.tty became NULL.

Thanks

Greg KH <[email protected]> 于2019年11月3日周日 下午8:42写道：
>
> On Sun, Nov 03, 2019 at 10:44:04AM +0800, hui yang wrote:
> > From: YangHui <[email protected]>
> >
> > Unable to handle kernel NULL pointer dereference at virtual address 000002a0
> > Kernel BUG at tty_wakeup+0x18/0x8c
> > [<0000000095135e9d>] tty_wakeup+0x18/0x8c
> > [<00000000c35f19e4>] gs_start_io+0xc8/0x158
> > [<00000000b11b184e>] gserial_connect+0xd0/0x174
> > [<00000000642201de>] acm_set_alt+0x70/0x180
> > [<00000000a9d38e8b>] composite_setup+0x1848/0x1a7c
> > [<0000000072c88781>] android_setup+0x1ec/0x1f4
> > [<000000004c0127a5>] msm_udc_irq+0x8d0/0xc0c
> > [<00000000f8bb9acf>] __handle_irq_event_percpu+0x74/0x294
> > [<00000000afd57256>] handle_irq_event+0x60/0xc8
> > [<0000000076719b24>] handle_fasteoi_irq+0xc8/0x1c4
> > [<00000000421f3d87>] generic_handle_irq+0x34/0x4c
> > [<00000000b2f2d343>] __handle_domain_irq+0x6c/0xbc
> > [<00000000c74325e8>] gic_handle_irq+0x6c/0xe0
> > yes,we can see the port->port.tty==NULL, so system crashed
> >
> > Signed-off-by: YangHui <[email protected]>
> > ---
> > drivers/usb/gadget/function/u_serial.c | 2 ++
> > 1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c
> > index 65f634e..a1c2ac2 100644
> > --- a/drivers/usb/gadget/function/u_serial.c
> > +++ b/drivers/usb/gadget/function/u_serial.c
> > @@ -562,6 +562,8 @@ static int gs_start_io(struct gs_port *port)
> >
> > /* unblock any pending writes into our circular buffer */
> > if (started) {
> > + if (port->port.tty == NULL)
> > + return -EIO;
>
> How can this happen? Shouldn't this be handled earlier?
>
> If not, can you document this how this can be true and what should be
> done about it?
>
> thanks,
>
> greg k-h

2019-11-13 07:14:54

by Peter Chen

Subject: Re: [PATCH 2/2] USB(u_serial.c): it has a NULL point

On 19-11-09 15:49:13, hui yang wrote:
> I'm sorry for my fault . Now I send to everyone .
>
> When we use USB to transmit data
> with PC, the phone will crashed Low probability .
> We found port->port.tty became NULL.

Would you please debug more, it seems gs open/close (gs_open/gs_close)
are something wrong. The value port->port.tty and port->port.count
are inconsistent.

Peter

>
> Thanks
>
> Greg KH <[email protected]> 于2019年11月3日周日 下午8:42写道：
> >
> > On Sun, Nov 03, 2019 at 10:44:04AM +0800, hui yang wrote:
> > > From: YangHui <[email protected]>
> > >
> > > Unable to handle kernel NULL pointer dereference at virtual address 000002a0
> > > Kernel BUG at tty_wakeup+0x18/0x8c
> > > [<0000000095135e9d>] tty_wakeup+0x18/0x8c
> > > [<00000000c35f19e4>] gs_start_io+0xc8/0x158
> > > [<00000000b11b184e>] gserial_connect+0xd0/0x174
> > > [<00000000642201de>] acm_set_alt+0x70/0x180
> > > [<00000000a9d38e8b>] composite_setup+0x1848/0x1a7c
> > > [<0000000072c88781>] android_setup+0x1ec/0x1f4
> > > [<000000004c0127a5>] msm_udc_irq+0x8d0/0xc0c
> > > [<00000000f8bb9acf>] __handle_irq_event_percpu+0x74/0x294
> > > [<00000000afd57256>] handle_irq_event+0x60/0xc8
> > > [<0000000076719b24>] handle_fasteoi_irq+0xc8/0x1c4
> > > [<00000000421f3d87>] generic_handle_irq+0x34/0x4c
> > > [<00000000b2f2d343>] __handle_domain_irq+0x6c/0xbc
> > > [<00000000c74325e8>] gic_handle_irq+0x6c/0xe0
> > > yes,we can see the port->port.tty==NULL, so system crashed
> > >
> > > Signed-off-by: YangHui <[email protected]>
> > > ---
> > > drivers/usb/gadget/function/u_serial.c | 2 ++
> > > 1 file changed, 2 insertions(+)
> > >
> > > diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c
> > > index 65f634e..a1c2ac2 100644
> > > --- a/drivers/usb/gadget/function/u_serial.c
> > > +++ b/drivers/usb/gadget/function/u_serial.c
> > > @@ -562,6 +562,8 @@ static int gs_start_io(struct gs_port *port)
> > >
> > > /* unblock any pending writes into our circular buffer */
> > > if (started) {
> > > + if (port->port.tty == NULL)
> > > + return -EIO;
> >
> > How can this happen? Shouldn't this be handled earlier?
> >
> > If not, can you document this how this can be true and what should be
> > done about it?
> >
> > thanks,
> >
> > greg k-h

--

Thanks,
Peter Chen