[PATCH 6.4 589/800] usb: gadget: u_serial: Add null pointer check in gserial_suspend

Greg Kroah-Hartman
2023-07-16T20:20:25Z

From: Prashanth K <quic_prashk@quicinc.com>

[ Upstream commit 2f6ecb89fe8feb2b60a53325b0eeb9866d88909a ]

Consider a case where gserial_disconnect has already cleared
gser->ioport. And if gserial_suspend gets called afterwards,
it will lead to accessing of gser->ioport and thus causing
null pointer dereference.

Avoid this by adding a null pointer check. Added a static
spinlock to prevent gser->ioport from becoming null after
the newly added null pointer check.

Fixes: aba3a8d01d62 ("usb: gadget: u_serial: add suspend resume callbacks")
Signed-off-by: Prashanth K <quic_prashk@quicinc.com>
Link: https://lore.kernel.org/r/1683278317-11774-1-git-send-email-quic_prashk@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/usb/gadget/function/u_serial.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c
index a0ca47fbff0fc..e5d522d54f6a3 100644
--- a/drivers/usb/gadget/function/u_serial.c
+++ b/drivers/usb/gadget/function/u_serial.c
@@ -1420,10 +1420,19 @@ 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);
}
--
2.39.2