On Sun 2019-04-07 07:59:01, Vadim Pasternak wrote:
> Fix the following UBSAN warning, reported undefined behavior at call to
> ror32():
> [ 11.426543] UBSAN: Undefined behaviour in ./include/linux/bitops.h:93:33
...
> The warning is caused by call to ror32(), if the second parameters of
> this function "shift" is zero. In such case UBSAN reports the warning
> for the next expression: (word << (32 - shift).
> Fix adds validation of this parameter ? in case it?s equal zero, no
> need to call rotation function, since value should stay the same.
>
> Fixes: 386570d76f2f ("leds: add driver for support Mellanox regmap LEDs for BMC and x86 platform")
> Reported-by: Ido Schimmel <idosch@xxxxxxxxxxxx>
> Signed-off-by: Vadim Pasternak <vadimp@xxxxxxxxxxxx>
Actually, rotating zero bits seems pretty valid operation. Could we
get that fixed, instead?
Thanks,
Pavel
> ---
> drivers/leds/leds-mlxreg.c | 18 ++++++++++++++----
> 1 file changed, 14 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/leds/leds-mlxreg.c b/drivers/leds/leds-mlxreg.c
> index cabe379071a7..ee6dd2a60002 100644
> --- a/drivers/leds/leds-mlxreg.c
> +++ b/drivers/leds/leds-mlxreg.c
> @@ -82,8 +82,13 @@ mlxreg_led_store_hw(struct mlxreg_led_data *led_data, u8 vset)
> if (ret)
> goto access_error;
>
> - nib = (ror32(data->mask, data->bit) == 0xf0) ? rol32(vset, data->bit) :
> - rol32(vset, data->bit + 4);
> + if (data->bit)
> + nib = (ror32(data->mask, data->bit) == 0xf0) ?
> + rol32(vset, data->bit) : rol32(vset, data->bit + 4);
> + else
> + nib = (data->mask == 0xf0) ? rol32(vset, data->bit) :
> + rol32(vset, data->bit + 4);
> +
> regval = (regval & data->mask) | nib;
>
> ret = regmap_write(led_pdata->regmap, data->reg, regval);
> @@ -122,8 +127,13 @@ mlxreg_led_get_hw(struct mlxreg_led_data *led_data)
> }
>
> regval = regval & ~data->mask;
> - regval = (ror32(data->mask, data->bit) == 0xf0) ? ror32(regval,
> - data->bit) : ror32(regval, data->bit + 4);
> + if (data->bit)
> + regval = (ror32(data->mask, data->bit) == 0xf0) ? ror32(regval,
> + data->bit) : ror32(regval, data->bit + 4);
> + else
> + regval = (data->mask == 0xf0) ? regval :
> + ror32(regval, data->bit + 4);
> +
> if (regval >= led_data->base_color &&
> regval <= (led_data->base_color + MLXREG_LED_OFFSET_BLINK_6HZ))
> return LED_FULL;
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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