2023-05-22 02:42:21

by Chunfeng Yun

Subject: [PATCH] usb: gadget: u_serial: Add null pointer check in gserial_suspend

When gserial_disconnect has already cleared gser->ioport, and the
suspend triggers afterwards, gserial_suspend gets called, which will
lead to accessing of gser->ioport and thus causing null pointer
dereference. Add a null pointer check to prevent it as the bellow
patch does:
5ec63fdbca60 ("usb: gadget: u_serial: Add null pointer check in gserial_resume")

Fixes: aba3a8d01d62 ("usb: gadget: u_serial: add suspend resume callbacks")
Cc: stable <[email protected]>
Signed-off-by: Chunfeng Yun <[email protected]>
---
drivers/usb/gadget/function/u_serial.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c
index a0ca47fbff0f..40ba220cf6d2 100644
--- a/drivers/usb/gadget/function/u_serial.c
+++ b/drivers/usb/gadget/function/u_serial.c
@@ -1420,10 +1420,18 @@ EXPORT_SYMBOL_GPL(gserial_disconnect);

void gserial_suspend(struct gserial *gser)
{
- struct gs_port *port = gser->ioport;
+ struct gs_port *port;
unsigned long flags;

- spin_lock_irqsave(&port->port_lock, flags);
+ spin_lock_irqsave(&serial_port_lock, flags);
+ port = gser->ioport;
+ if (!port) {
+ spin_unlock_irqrestore(&serial_port_lock, flags);
+ return;
+ }
+
+ spin_lock(&port->port_lock);
+ spin_unlock(&serial_port_lock);
port->suspended = true;
spin_unlock_irqrestore(&port->port_lock, flags);
}
--
2.18.0

2023-05-22 06:03:30

by Prashanth K

Subject: Re: [PATCH] usb: gadget: u_serial: Add null pointer check in gserial_suspend

On 22-05-23 07:51 am, Chunfeng Yun wrote:
> When gserial_disconnect has already cleared gser->ioport, and the
> suspend triggers afterwards, gserial_suspend gets called, which will
> lead to accessing of gser->ioport and thus causing null pointer
> dereference. Add a null pointer check to prevent it as the bellow
> patch does:
> 5ec63fdbca60 ("usb: gadget: u_serial: Add null pointer check in gserial_resume")
>
> Fixes: aba3a8d01d62 ("usb: gadget: u_serial: add suspend resume callbacks")
> Cc: stable <[email protected]>
> Signed-off-by: Chunfeng Yun <[email protected]>
> ---
> drivers/usb/gadget/function/u_serial.c | 12 ++++++++++--
> 1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c
> index a0ca47fbff0f..40ba220cf6d2 100644
> --- a/drivers/usb/gadget/function/u_serial.c
> +++ b/drivers/usb/gadget/function/u_serial.c
> @@ -1420,10 +1420,18 @@ EXPORT_SYMBOL_GPL(gserial_disconnect);
>
> void gserial_suspend(struct gserial *gser)
> {
> - struct gs_port *port = gser->ioport;
> + struct gs_port *port;
> unsigned long flags;
>
> - spin_lock_irqsave(&port->port_lock, flags);
> + spin_lock_irqsave(&serial_port_lock, flags);
> + port = gser->ioport;
> + if (!port) {
> + spin_unlock_irqrestore(&serial_port_lock, flags);
> + return;
> + }
> +
> + spin_lock(&port->port_lock);
> + spin_unlock(&serial_port_lock);
> port->suspended = true;
> spin_unlock_irqrestore(&port->port_lock, flags);
> }
Hi Chunfeng,

This looks same as the following patch.
https://lore.kernel.org/linux-usb/[email protected]/


Regards

2023-05-25 07:13:40

by Chunfeng Yun

Subject: Re: [PATCH] usb: gadget: u_serial: Add null pointer check in gserial_suspend

On Mon, 2023-05-22 at 11:19 +0530, Prashanth K wrote:
> External email : Please do not click links or open attachments until
> you have verified the sender or the content.
>
>
> On 22-05-23 07:51 am, Chunfeng Yun wrote:
> > When gserial_disconnect has already cleared gser->ioport, and the
> > suspend triggers afterwards, gserial_suspend gets called, which
> > will
> > lead to accessing of gser->ioport and thus causing null pointer
> > dereference. Add a null pointer check to prevent it as the bellow
> > patch does:
> > 5ec63fdbca60 ("usb: gadget: u_serial: Add null pointer check in
> > gserial_resume")
> >
> > Fixes: aba3a8d01d62 ("usb: gadget: u_serial: add suspend resume
> > callbacks")
> > Cc: stable <[email protected]>
> > Signed-off-by: Chunfeng Yun <[email protected]>
> > ---
> > drivers/usb/gadget/function/u_serial.c | 12 ++++++++++--
> > 1 file changed, 10 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/usb/gadget/function/u_serial.c
> > b/drivers/usb/gadget/function/u_serial.c
> > index a0ca47fbff0f..40ba220cf6d2 100644
> > --- a/drivers/usb/gadget/function/u_serial.c
> > +++ b/drivers/usb/gadget/function/u_serial.c
> > @@ -1420,10 +1420,18 @@ EXPORT_SYMBOL_GPL(gserial_disconnect);
> >
> > void gserial_suspend(struct gserial *gser)
> > {
> > - struct gs_port *port = gser->ioport;
> > + struct gs_port *port;
> > unsigned long flags;
> >
> > - spin_lock_irqsave(&port->port_lock, flags);
> > + spin_lock_irqsave(&serial_port_lock, flags);
> > + port = gser->ioport;
> > + if (!port) {
> > + spin_unlock_irqrestore(&serial_port_lock, flags);
> > + return;
> > + }
> > +
> > + spin_lock(&port->port_lock);
> > + spin_unlock(&serial_port_lock);
> > port->suspended = true;
> > spin_unlock_irqrestore(&port->port_lock, flags);
> > }
>
> Hi Chunfeng,
>
> This looks same as the following patch.
>
https://lore.kernel.org/linux-usb/[email protected]/

Yes, it is, please ignore this one, thanks a lot

>
>
> Regards