If gs_close has cleared port->port.tty and gs_start_io is called
afterwards, then the function tty_wakeup will attempt to access the value
of the pointer port->port.tty which will cause a null pointer
dereference error.
To avoid this, add a null pointer check to gs_start_io before attempting
to access the value of the pointer port->port.tty.
Signed-off-by: Kuen-Han Tsai <khtsai@xxxxxxxxxx>
---
drivers/usb/gadget/function/u_serial.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c
index 97f07757d19e..1115396b46a0 100644
--- a/drivers/usb/gadget/function/u_serial.c
+++ b/drivers/usb/gadget/function/u_serial.c
@@ -539,16 +539,20 @@ static int gs_alloc_requests(struct usb_ep *ep, struct list_head *head,
static int gs_start_io(struct gs_port *port)
{
struct list_head *head = &port->read_pool;
- struct usb_ep *ep = port->port_usb->out;
+ struct usb_ep *ep;
int status;
unsigned started;
+ if (!port->port_usb || !port->port.tty)
+ return -EIO;
+
/* Allocate RX and TX I/O buffers. We can't easily do this much
* earlier (with GFP_KERNEL) because the requests are coupled to
* endpoints, as are the packet sizes we'll be using. Different
* configurations may use different endpoints with a given port;
* and high speed vs full speed changes packet sizes too.
*/
+ ep = port->port_usb->out;
status = gs_alloc_requests(ep, head, gs_read_complete,
&port->read_allocated);
if (status)
--
2.41.0.rc0.172.g3f132b7071-goog
