On Sat, Jan 28, 2023 at 05:13:19AM -0800, Guenter Roeck wrote: > On Fri, Jan 27, 2023 at 02:37:45PM -0800, Kees Cook wrote: > > The index into various register arrays was not bounds checked. Add > > checking. Seen under GCC 13: > > > > drivers/hwmon/lm85.c: In function 'pwm_auto_pwm_minctl_store': > > drivers/hwmon/lm85.c:1110:26: warning: array subscript [0, 31] is outside array bounds of 'struct lm85_autofan[3]' [-Warray-bounds=] > > 1110 | if (data->autofan[nr].min_off) > > | ~~~~~~~~~~~~~^~~~ > > drivers/hwmon/lm85.c:317:29: note: while referencing 'autofan' > > 317 | struct lm85_autofan autofan[3]; > > | ^~~~~~~ > > > > This is a false positive. The value can never be >= 3. > It is derived from the last value of the following > SENSOR_DEVICE_ATTR_RW() entries. > > I resist making changes like this to the code just because > the compiler can not determine the range of a variable. > It blows up code size amd makes it hard to read just to > make the compiler happy. I think it's worth it given the index is an "int" and it'd be very easy for things to go wrong in the face of other memory corruption, etc. I've sent a v2 that I think is much more readable and non-invasive but provides similar robustness. -Kees -- Kees Cook
