[PATCH] pinctrl: single: Fix potential division by zero

[Maxim Korotkov <korotkov.maxim.s@gmail.com>]

There is a possibility of dividing by zero due to the pcs->bits_per_pin
if pcs->fmask() also has a value of zero and called fls
from asm-generic/bitops/builtin-fls.h or arch/x86/include/asm/bitops.h.
The function pcs_probe() has the branch that assigned to fmask 0 before
pcs_allocate_pin_table() was called

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 4e7e8017a80e ("pinctrl: pinctrl-single: enhance to configure multiple pins of different modules")
Signed-off-by: Maxim Korotkov <korotkov.maxim.s@gmail.com>
---
 drivers/pinctrl/pinctrl-single.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pinctrl/pinctrl-single.c b/drivers/pinctrl/pinctrl-single.c
index 67bec7ea0f8b..414ee6bb8ac9 100644
--- a/drivers/pinctrl/pinctrl-single.c
+++ b/drivers/pinctrl/pinctrl-single.c
@@ -727,7 +727,7 @@ static int pcs_allocate_pin_table(struct pcs_device *pcs)
 
 	mux_bytes = pcs->width / BITS_PER_BYTE;
 
-	if (pcs->bits_per_mux) {
+	if (pcs->bits_per_mux && pcs->fmask) {
 		pcs->bits_per_pin = fls(pcs->fmask);
 		nr_pins = (pcs->size * BITS_PER_BYTE) / pcs->bits_per_pin;
 	} else {
-- 
2.17.1