serial: mctrl_gpio: Check for NULL pointer

PATCH In review Adam Ford 2 participants 4 messages Oct 6, 2019 TTY layer and serial drivers

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Adam Ford

author

2019-10-06 16:33 UTC #0 lore raw

PATCH v2 1/2 serial: mctrl_gpio: Check for NULL pointer

When using mctrl_gpio_to_gpiod, it dereferences gpios into a single requested GPIO. This dereferencing can break if gpios is NULL, so this patch adds a NULL check before dereferencing it. If gpios is NULL, this function will also return NULL.

Signed-off-by Adam Ford <[email protected]>

---
V2: This patch is new to the V2 of this series, so patch 2/2 can
work without risking a NULL dereference

drivers/tty/serial/serial_mctrl_gpio.c +3 -0

index d9074303c88e..fb4781292d40 100644
@@ -66,6 +66,9 @@ EXPORT_SYMBOL_GPL(mctrl_gpio_set);
 struct gpio_desc *mctrl_gpio_to_gpiod(struct mctrl_gpios *gpios,
 				      enum mctrl_gpio_idx gidx)
 {
+	if (gpios == NULL)
+		return NULL;
+
 	return gpios->gpio[gidx];
 }
 EXPORT_SYMBOL_GPL(mctrl_gpio_to_gpiod);

Signature · 1 line

2.17.1

Adam Ford

author

2019-10-06 16:33 UTC #1 lore raw

PATCH v2 2/2 serial: 8250_omap: Fix gpio check for auto RTS/CTS

There are two checks to see if the manual gpio is configured, but these the check is seeing if the structure is NULL instead it should check to see if there are CTS and/or RTS pins defined.

This patch uses checks for those individual pins instead of checking for the structure itself to restore auto RTS/CTS.

Signed-off-by Adam Ford <[email protected]>

---
V2: Made the NULL dererence check from patch 1/2 come before this.

drivers/tty/serial/8250/8250_omap.c +3 -2

index c68e2b3a1634..836e736ae188 100644
@@ -141,7 +141,7 @@ static void omap8250_set_mctrl(struct uart_port *port, unsigned int mctrl)
 
 	serial8250_do_set_mctrl(port, mctrl);
 
-	if (!up->gpios) {
+	if (!mctrl_gpio_to_gpiod(up->gpios, UART_GPIO_RTS)) {
 		/*
 		 * Turn off autoRTS if RTS is lowered and restore autoRTS
 		 * setting if RTS is raised

@@ -456,7 +456,8 @@ static void omap_8250_set_termios(struct uart_port *port,
 	up->port.status &= ~(UPSTAT_AUTOCTS | UPSTAT_AUTORTS | UPSTAT_AUTOXOFF);
 
 	if (termios->c_cflag & CRTSCTS && up->port.flags & UPF_HARD_FLOW &&
-	    !up->gpios) {
+	    !mctrl_gpio_to_gpiod(up->gpios, UART_GPIO_RTS) &&
+	    !mctrl_gpio_to_gpiod(up->gpios, UART_GPIO_CTS)) {
 		/* Enable AUTOCTS (autoRTS is enabled when RTS is raised) */
 		up->port.status |= UPSTAT_AUTOCTS | UPSTAT_AUTORTS;
 		priv->efr |= UART_EFR_CTS;

Signature · 1 line

2.17.1

Yegor Yefremov

Reviewed-by on v2 2/2

2019-10-06 18:11 UTC #2 lore raw

Re: [PATCH V2 2/2] serial: 8250_omap: Fix gpio check for auto RTS/CTS

Quoted 9 lines · Adam Ford

There are two checks to see if the manual gpio is configured, but these the check is seeing if the structure is NULL instead it should check to see if there are CTS and/or RTS pins defined.
This patch uses checks for those individual pins instead of checking for the structure itself to restore auto RTS/CTS.
Signed-off-by Adam Ford <[email protected]>

Reviewed-by Yegor Yefremov <[email protected]>

Quoted 29 lines

---
V2: Made the NULL dererence check from patch 1/2 come before this.

drivers/tty/serial/8250/8250_omap.c +3 -3

index c68e2b3a1634..836e736ae188 100644
@@ -141,7 +141,7 @@ static void omap8250_set_mctrl(struct uart_port *port, unsigned int mctrl)
 
        serial8250_do_set_mctrl(port, mctrl);
 
-       if (!up->gpios) {
+       if (!mctrl_gpio_to_gpiod(up->gpios, UART_GPIO_RTS)) {
                /*
                 * Turn off autoRTS if RTS is lowered and restore autoRTS
                 * setting if RTS is raised

@@ -456,7 +456,8 @@ static void omap_8250_set_termios(struct uart_port *port,
        up->port.status &= ~(UPSTAT_AUTOCTS | UPSTAT_AUTORTS | UPSTAT_AUTOXOFF);
 
        if (termios->c_cflag & CRTSCTS && up->port.flags & UPF_HARD_FLOW &&
-           !up->gpios) {
+           !mctrl_gpio_to_gpiod(up->gpios, UART_GPIO_RTS) &&
+           !mctrl_gpio_to_gpiod(up->gpios, UART_GPIO_CTS)) {
                /* Enable AUTOCTS (autoRTS is enabled when RTS is raised) */
                up->port.status |= UPSTAT_AUTOCTS | UPSTAT_AUTORTS;
                priv->efr |= UART_EFR_CTS;
--

2.17.1

Yegor Yefremov

Reviewed-by on v2 1/2

2019-10-06 18:11 UTC #3 lore raw

In reply to Adam Ford

Quoted 7 lines · Adam Ford

When using mctrl_gpio_to_gpiod, it dereferences gpios into a single requested GPIO. This dereferencing can break if gpios is NULL, so this patch adds a NULL check before dereferencing it. If gpios is NULL, this function will also return NULL.
Signed-off-by Adam Ford <[email protected]>

Reviewed-by Yegor Yefremov <[email protected]>

Quoted 20 lines

---
V2: This patch is new to the V2 of this series, so patch 2/2 can
work without risking a NULL dereference

drivers/tty/serial/serial_mctrl_gpio.c +3 -1

index d9074303c88e..fb4781292d40 100644
@@ -66,6 +66,9 @@ EXPORT_SYMBOL_GPL(mctrl_gpio_set);
 struct gpio_desc *mctrl_gpio_to_gpiod(struct mctrl_gpios *gpios,
                                      enum mctrl_gpio_idx gidx)
 {
+       if (gpios == NULL)
+               return NULL;
+
        return gpios->gpio[gidx];
 }
 EXPORT_SYMBOL_GPL(mctrl_gpio_to_gpiod);
--

2.17.1