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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 <fugang.duan@nxp.com>
Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Tested-by: Fugang Duan <fugang.duan@nxp.com>
Acked-by: Fugang Duan <fugang.duan@nxp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Fabio Estevam 2016-05-20 01:59:54 -03:00 committed by Greg Kroah-Hartman
parent 3e5af8e04a
commit a7cfaf165e
1 changed files with 4 additions and 4 deletions
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8
drivers/tty/serial/serial_core.c
View File

@ -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);