From: Kees Cook keescook@chromium.org
[ Upstream commit 4265eb062a7303e537ab3792ade31f424c3c5189 ]
Without visibility into the initializers for data->innr, GCC suspects using it as an index could walk off the end of the various 14-element arrays in data. Perform an explicit clamp to the array size. Silences the following warning with GCC 12+:
../drivers/hwmon/pc87360.c: In function 'pc87360_update_device': ../drivers/hwmon/pc87360.c:341:49: warning: writing 1 byte into a region of size 0 [-Wstringop-overflow=] 341 | data->in_max[i] = pc87360_read_value(data, | ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~ 342 | LD_IN, i, | ~~~~~~~~~ 343 | PC87365_REG_IN_MAX); | ~~~~~~~~~~~~~~~~~~~ ../drivers/hwmon/pc87360.c:209:12: note: at offset 255 into destination object 'in_max' of size 14 209 | u8 in_max[14]; /* Register value */ | ^~~~~~
Cc: Jim Cromie jim.cromie@gmail.com Cc: Jean Delvare jdelvare@suse.com Cc: Guenter Roeck linux@roeck-us.net Cc: linux-hwmon@vger.kernel.org Signed-off-by: Kees Cook keescook@chromium.org Reviewed-by: Gustavo A. R. Silva gustavoars@kernel.org Link: https://lore.kernel.org/r/20231130200207.work.679-kees@kernel.org [groeck: Added comment into code clarifying context] Signed-off-by: Guenter Roeck linux@roeck-us.net Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/hwmon/pc87360.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/hwmon/pc87360.c b/drivers/hwmon/pc87360.c index a4adc8bd531f..534a6072036c 100644 --- a/drivers/hwmon/pc87360.c +++ b/drivers/hwmon/pc87360.c @@ -323,7 +323,11 @@ static struct pc87360_data *pc87360_update_device(struct device *dev) }
/* Voltages */ - for (i = 0; i < data->innr; i++) { + /* + * The min() below does not have any practical meaning and is + * only needed to silence a warning observed with gcc 12+. + */ + for (i = 0; i < min(data->innr, ARRAY_SIZE(data->in)); i++) { data->in_status[i] = pc87360_read_value(data, LD_IN, i, PC87365_REG_IN_STATUS); /* Clear bits */