From: Prashanth K quic_prashk@quicinc.com
commit 5ec63fdbca604568890c577753c6f66c5b3ef0b5 upstream.
Consider a case where gserial_disconnect has already cleared gser->ioport. And if a wakeup interrupt triggers afterwards, gserial_resume gets called, which will lead to accessing of gser->ioport and thus causing null pointer dereference.Add a null pointer check to prevent this.
Added a static spinlock to prevent gser->ioport from becoming null after the newly added check.
Fixes: aba3a8d01d62 ("usb: gadget: u_serial: add suspend resume callbacks") Cc: stable stable@kernel.org Signed-off-by: Prashanth K quic_prashk@quicinc.com Acked-by: Alan Stern stern@rowland.harvard.edu Link: https://lore.kernel.org/r/1676309438-14922-1-git-send-email-quic_prashk@quic... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/usb/gadget/function/u_serial.c | 23 +++++++++++++++++++---- 1 file changed, 19 insertions(+), 4 deletions(-)
--- a/drivers/usb/gadget/function/u_serial.c +++ b/drivers/usb/gadget/function/u_serial.c @@ -81,6 +81,9 @@ #define WRITE_BUF_SIZE 8192 /* TX only */ #define GS_CONSOLE_BUF_SIZE 8192
+/* Prevents race conditions while accessing gser->ioport */ +static DEFINE_SPINLOCK(serial_port_lock); + /* console info */ struct gs_console { struct console console; @@ -1376,8 +1379,10 @@ void gserial_disconnect(struct gserial * if (!port) return;
+ spin_lock_irqsave(&serial_port_lock, flags); + /* tell the TTY glue not to do I/O here any more */ - spin_lock_irqsave(&port->port_lock, flags); + spin_lock(&port->port_lock);
gs_console_disconnect(port);
@@ -1392,7 +1397,8 @@ void gserial_disconnect(struct gserial * tty_hangup(port->port.tty); } port->suspended = false; - spin_unlock_irqrestore(&port->port_lock, flags); + spin_unlock(&port->port_lock); + spin_unlock_irqrestore(&serial_port_lock, flags);
/* disable endpoints, aborting down any active I/O */ usb_ep_disable(gser->out); @@ -1426,10 +1432,19 @@ EXPORT_SYMBOL_GPL(gserial_suspend);
void gserial_resume(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 = false; if (!port->start_delayed) { spin_unlock_irqrestore(&port->port_lock, flags);