Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 5.10 210/593] spi: Avoid undefined behaviour when counting unused native CSs | Date | Mon, 12 Jul 2021 08:06:10 +0200 |
| |
From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
[ 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> --- drivers/spi/spi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
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) { -- 2.30.2
| |