diff options
| author | Andy Shevchenko <andriy.shevchenko@linux.intel.com> | 2021-04-20 19:44:25 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-07-14 16:56:02 +0200 |
| commit | 08d0aa16a1f7fac53a158080e16f4aa09f19a763 (patch) | |
| tree | 779b9fe3baae596cf8c65c0243c65f51d029a74f /drivers | |
| parent | db5a7e22c96c473ffed77990b8febfec6be287cd (diff) | |
spi: Avoid undefined behaviour when counting unused native CSs
[ Upstream commit f60d7270c8a3d2beb1c23ae0da42497afa3584c2 ]
ffz(), that has been used to count unused native CSs,
might cause undefined behaviour when called against ~0U.
To fix that, open code it with ffs(~value) - 1.
Fixes: 7d93aecdb58d ("spi: Add generic support for unused native cs with cs-gpios")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20210420164425.40287-2-andriy.shevchenko@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/spi/spi.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index a1a85f0baf7c..8c261eac2cee 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -2614,7 +2614,7 @@ static int spi_get_gpio_descs(struct spi_controller *ctlr) native_cs_mask |= BIT(i); } - ctlr->unused_native_cs = ffz(native_cs_mask); + ctlr->unused_native_cs = ffs(~native_cs_mask) - 1; if ((ctlr->flags & SPI_MASTER_GPIO_SS) && num_cs_gpios && ctlr->max_native_cs && ctlr->unused_native_cs >= ctlr->max_native_cs) { |