From 5fe625c136367fc7283d021d3ae574fce060d716 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Thu, 6 Jun 2019 17:52:42 +0900 Subject: [PATCH] hwmon: (smsc47m1) fix (suspicious) outside array bounds warnings Kbuild test robot reports outside array bounds warnings. This is reproducible for ARCH=sh allmodconfig with the kernel.org toolchains available at: https://mirrors.edge.kernel.org/pub/tools/crosstool/files/bin/x86_64/8.1.0/x86_64-gcc-8.1.0-nolibc-sh4-linux.tar.xz CC [M] drivers/hwmon/smsc47m1.o drivers/hwmon/smsc47m1.c: In function 'fan_div_store': drivers/hwmon/smsc47m1.c:370:49: warning: array subscript [0, 2] is outside array bounds of 'u8[3]' {aka 'unsigned char[3]'} [-Warray-bounds] tmp = 192 - (old_div * (192 - data->fan_preload[nr]) ~~~~~~~~~~~~~~~~~^~~~ drivers/hwmon/smsc47m1.c:372:19: warning: array subscript [0, 2] is outside array bounds of 'u8[3]' {aka 'unsigned char[3]'} [-Warray-bounds] data->fan_preload[nr] = clamp_val(tmp, 0, 191); ~~~~~~~~~~~~~~~~~^~~~ drivers/hwmon/smsc47m1.c:373:53: warning: array subscript [0, 2] is outside array bounds of 'const u8[3]' {aka 'const unsigned char[3]'} [-Warray-bounds] smsc47m1_write_value(data, SMSC47M1_REG_FAN_PRELOAD[nr], ~~~~~~~~~~~~~~~~~~~~~~~~^~~~ Looking at the code, I believe these are false positives. While it is ridiculous to patch our driver to make the insane compiler happy, clarifying the unreachable path will be helpful not only for compilers but also for humans. Reported-by: kbuild test robot Signed-off-by: Masahiro Yamada [groeck: Use BUG() instead of unreachable() to make objtool happy] Signed-off-by: Guenter Roeck --- drivers/hwmon/smsc47m1.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/hwmon/smsc47m1.c b/drivers/hwmon/smsc47m1.c index cc6aca6e436c..b637836b58a1 100644 --- a/drivers/hwmon/smsc47m1.c +++ b/drivers/hwmon/smsc47m1.c @@ -351,6 +351,8 @@ static ssize_t fan_div_store(struct device *dev, tmp |= data->fan_div[2] << 4; smsc47m1_write_value(data, SMSC47M2_REG_FANDIV3, tmp); break; + default: + BUG(); } /* Preserve fan min */