2022-11-17 12:54:45

by Maxim Korotkov

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

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 <[email protected]>
---
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

2022-11-18 08:29:52

by Tony Lindgren

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

* Maxim Korotkov <[email protected]> [221117 12:22]:
> 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

Reviewed-by: Tony Lindgren <[email protected]>

2022-11-21 14:04:52

by Linus Walleij

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

On Thu, Nov 17, 2022 at 1:32 PM Maxim Korotkov
<[email protected]> wrote:

> 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 <[email protected]>

Patch applied for fixes.

Yours,
Linus Walleij