pinctrl: single: Fix potential division by zero

[ Upstream commit 64c150339e7f6c5cbbe8c17a56ef2b3902612798 ]

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>
Reviewed-by: Tony Lindgren <tony@atomide.com>
Link: https://lore.kernel.org/r/20221117123034.27383-1-korotkov.maxim.s@gmail.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/pinctrl/pinctrl-single.c b/drivers/pinctrl/pinctrl-single.c
index 67bec7e..414ee6b 100644 (file)
--- 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 {