pinctrl: thead1520: Fix Null pointer dereference

pinmux_generic_get_function may return NULL, and its retval is
dereferenced without check, which will cause a NULL pointer
dereference.

Signed-off-by: clingfei <[email protected]>
Reviewed-by: Drew Fustini <[email protected]>
Link: https://lore.kernel.org/[email protected]
Signed-off-by: Linus Walleij <[email protected]>

Author: clf700383

drivers/pinctrl/pinctrl-th1520.c

@@ -798,6 +798,8 @@ static int th1520_pinmux_set_mux(struct pinctrl_dev *pctldev,
 	struct th1520_pinctrl *thp = pinctrl_dev_get_drvdata(pctldev);
 	const struct function_desc *func = pinmux_generic_get_function(pctldev, fsel);
 
+	if (!func)
+		return -EINVAL;
 	return th1520_pinmux_set(thp, thp->desc.pins[gsel].number,
 				 (uintptr_t)thp->desc.pins[gsel].drv_data & TH1520_PAD_MUXDATA,
 				 (uintptr_t)func->data);