From a7cfaf165ed0f0b1e5e8636f9f28843b2b90139a Mon Sep 17 00:00:00 2001 From: Fabio Estevam Date: Fri, 20 May 2016 01:59:54 -0300 Subject: [PATCH] serial: serial_core: Perform NULL checks for release/request_port ops Doing the following UART bind/unbind sequence on a i.mx platform causes a kernel crash due to NULL pointer dereference: echo 21f4000.serial > /sys/bus/platform/drivers/imx-uart/bind echo 21f4000.serial > /sys/bus/platform/drivers/imx-uart/unbind Fix this problem by adding NULL checks prior to calling release/request_port ops. Reported-by: Fugang Duan Signed-off-by: Fabio Estevam Tested-by: Fugang Duan Acked-by: Fugang Duan Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/serial_core.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index a333c59cba2c..9fc15335c8c5 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -887,7 +887,7 @@ static int uart_set_info(struct tty_struct *tty, struct tty_port *port, /* * Free and release old regions */ - if (old_type != PORT_UNKNOWN) + if (old_type != PORT_UNKNOWN && uport->ops->release_port) uport->ops->release_port(uport); uport->iobase = new_port; @@ -900,7 +900,7 @@ static int uart_set_info(struct tty_struct *tty, struct tty_port *port, /* * Claim and map the new regions */ - if (uport->type != PORT_UNKNOWN) { + if (uport->type != PORT_UNKNOWN && uport->ops->request_port) { retval = uport->ops->request_port(uport); } else { /* Always success - Jean II */ @@ -1125,7 +1125,7 @@ static int uart_do_autoconfig(struct tty_struct *tty,struct uart_state *state) * If we already have a port type configured, * we must release its resources. */ - if (uport->type != PORT_UNKNOWN) + if (uport->type != PORT_UNKNOWN && uport->ops->release_port) uport->ops->release_port(uport); flags = UART_CONFIG_TYPE; @@ -2897,7 +2897,7 @@ int uart_remove_one_port(struct uart_driver *drv, struct uart_port *uport) /* * Free the port IO and memory resources, if any. */ - if (uport->type != PORT_UNKNOWN) + if (uport->type != PORT_UNKNOWN && uport->ops->release_port) uport->ops->release_port(uport); kfree(uport->tty_groups);