As per https://bugs.kde.org/show_bug.cgi?id=376537 ksysguard crashes, when /proc/stat returns the following file:
cpu0 x y z
cpu3 x y z
The issue is that it counts two CPUs, and later allocates two entries for the array, but uses the CPU number to index that array. An array with indices 0 and 3 should have 4 entries, not 2.