* Boot with the kernel argument console=ttyUSB0,9600
* Run: stty -a < /dev/ttyUSB0
* Immediately you get an oops warning, which later leads to a hard
kernel crash
The commit 335f8514f200e63d689113d29cb7253a5c282967 created the
original regression and commit
6e4061210150d1d6d388c5fba05f6b49a306a27e only fixed part of the
problem.
Only protect the serial->type->open() from getting executed when the
device is used as a console.
The wider scope of the console protection added in
6e4061210150d1d6d388c5fba05f6b49a306a27e causes the logic in
serial_open() to fall through and zero out the port->port.count with
the stty sys call. Once the port.count is zeroed the HW will get
closed while other drivers still have call backs to a non-initialized
device which crashes the kernel.
Signed-off-by: Jason Wessel <jason.wessel@xxxxxxxxxxxxx>
Cc: Greg KH <gregkh@xxxxxxx>
Cc: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
---
drivers/usb/serial/usb-serial.c | 17 ++++++++++-------
1 files changed, 10 insertions(+), 7 deletions(-)
diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 99188c9..7ca4ced 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -223,8 +223,7 @@ static int serial_open (struct tty_struct *tty, struct file *filp)
tty->driver_data = port;
tty_port_tty_set(&port->port, tty);
- /* If the console is attached, the device is already open */
- if (port->port.count == 1 && !port->console) {
+ if (port->port.count == 1) {
first = 1;
/* lock this module before we call it
* this may fail, which means we must bail out,
@@ -242,11 +241,15 @@ static int serial_open (struct tty_struct *tty, struct file *filp)
if (retval)
goto bailout_module_put;
- /* only call the device specific open if this
- * is the first time the port is opened */
- retval = serial->type->open(tty, port, filp);
- if (retval)
- goto bailout_interface_put;
+ /* only call the device specific open if this is the
+ * first time the port is opened and it is not a
+ * console port where the HW has already been
+ * initialized */
+ if (!port->console) {
+ retval = serial->type->open(tty, port, filp);
+ if (retval)
+ goto bailout_interface_put;
+ }
mutex_unlock(&serial->disc_mutex);
set_bit(ASYNCB_INITIALIZED, &port->port.flags);
}
--
1.6.3.1.9.g95405b
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