diff options
| author | Alan Cox <alan@linux.intel.com> | 2012-09-19 15:35:46 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2012-09-21 09:51:09 -0700 |
| commit | 43eca0aef73cc6f0d37ad139f1cbb810e62e409d (patch) | |
| tree | cbfe2836fa83eacbb4f08f31cb982fa20c8a8d80 /drivers/tty/serial/serial_core.c | |
| parent | 84c3b84860440a9e3a3666c14112f41311b8f623 (diff) | |
serial_core: Fix race in uart_handle_dcd_change
If a serial driver is called post hangup with a second DCD event then we
will attempt to get the ldisc of NULL. Check we have a tty before trying to
do anything with it.
This is still only safe within the uart layer if the caller holds the
relevant uart locks. We could do with a version where the tty is passed for
more general use.
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/serial/serial_core.c')
| -rw-r--r-- | drivers/tty/serial/serial_core.c | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index 046279ce3e8..78036c510cc 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -2501,9 +2501,12 @@ void uart_handle_dcd_change(struct uart_port *uport, unsigned int status) { struct uart_state *state = uport->state; struct tty_port *port = &state->port; - struct tty_ldisc *ld = tty_ldisc_ref(port->tty); + struct tty_ldisc *ld = NULL; struct pps_event_time ts; + struct tty_struct *tty = port->tty; + if (tty) + ld = tty_ldisc_ref(tty); if (ld && ld->ops->dcd_change) pps_get_ts(&ts); @@ -2516,12 +2519,12 @@ void uart_handle_dcd_change(struct uart_port *uport, unsigned int status) if (port->flags & ASYNC_CHECK_CD) { if (status) wake_up_interruptible(&port->open_wait); - else if (port->tty) - tty_hangup(port->tty); + else if (tty) + tty_hangup(tty); } if (ld && ld->ops->dcd_change) - ld->ops->dcd_change(port->tty, status, &ts); + ld->ops->dcd_change(tty, status, &ts); if (ld) tty_ldisc_deref(ld); } |