pinctrl: th1520: Fix potential null pointer dereference on func

The initialization of muxtype deferences pointer func before func
is sanity checked with a null pointer check, hence we have a null
pointer deference issue. Fix this by only deferencing func with
the assignment to muxtype after func has been null pointer checked.

Fixes: 1fc30cd ("pinctrl: th1520: Factor out casts")
Signed-off-by: Colin Ian King <[email protected]>
Reported-by: Kees Bakker <[email protected]>
Acked-by: Drew Fustini <[email protected]>
Link: https://lore.kernel.org/[email protected]
Signed-off-by: Linus Walleij <[email protected]>

Author: ColinIanKing

drivers/pinctrl/pinctrl-th1520.c

@@ -803,11 +803,12 @@ 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);
-	enum th1520_muxtype muxtype = (uintptr_t)func->data;
+	enum th1520_muxtype muxtype;
 
 	if (!func)
 		return -EINVAL;
 
+	muxtype = (uintptr_t)func->data;
 	return th1520_pinmux_set(thp, thp->desc.pins[gsel].number,
 				 th1520_pad_muxdata(thp->desc.pins[gsel].drv_data),
 				 muxtype);