sanitizer¶

Small address sanitizer runtime.

Compiler will insert calls to functions in this file for each pointer write/read, we then check if the address is “unavailable” and show a warning.

You can tweak this module’s behavior with the following flags on your makefile (set them to either 0 or 1)

KASAN_GLOBALS: track global variables
KASAN_STACK: extra checks on stack variables… Seems to crash as of now
KASAN_ALLOCAS: extra checks for alloca() and VLA
KASAN_MALLOC: wrap dynamic memory allocation, to mark it as available

Warning

To set this module up you need to define a custom linker script, defining the area in which the sanitizer stores information You must provide __kasan_shadow_base__ (8-byte aligned) and __kasan_shadow_end__ as the memory region where to work.

To do that on my RP2040, i’ve edited ChibiOS’ linker script such that ram0 is now 8/9 of its original size, and the last 1/9 (now ram2) is used by sanitizer.

These numbers come from the fact that for tracking whether each memory location (byte) is available, we use a single bit. As such, the memory needed would be 1/8 of total RAM, but since we dont want to track this memory itself, we can do 1/9.

Danger

Adds significant RAM usage and some code slow down.

Only use it for debugging, or if your MCU has enough resources.