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usb: gadget: u_serial: Add null pointer check in gserial_resume 

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: aba3a8d01d ("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@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Prashanth K 2023-02-13 23:00:38 +05:30 committed by Greg Kroah-Hartman
parent 7ebb605d22
commit 5ec63fdbca
1 changed files with 19 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
drivers/usb/gadget/function/u_serial.c
View File

@ -82,6 +82,9 @@
#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;
@ -1375,8 +1378,10 @@ void gserial_disconnect(struct gserial *gser)
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);
@ -1391,7 +1396,8 @@ void gserial_disconnect(struct gserial *gser)
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);
@ -1425,10 +1431,19 @@ 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);