This feature let us to detect accesses out of bounds of global variables. This will work as for globals in kernel image, so for globals in modules. Currently this won't work for symbols in user-specified sections (e.g. __init, __read_mostly, ...) The idea of this is simple. Compiler increases each global variable by redzone size and add constructors invoking __asan_register_globals() function. Information about global variable (address, size, size with redzone ...) passed to __asan_register_globals() so we could poison variable's redzone. This patch also forces module_alloc() to return 8*PAGE_SIZE aligned address making shadow memory handling ( kasan_module_alloc()/kasan_module_free() ) more simple. Such alignment guarantees that each shadow page backing modules address space correspond to only one module_alloc() allocation.
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| @@ -9,7 +9,7 @@ CFLAGS_KASAN_MINIMAL := -fsanitize=kernel-address · 8 unmodified lines | |||
| 9 | 9 | ||
| 10 | CFLAGS_KASAN := $(call cc-option, -fsanitize=kernel-address \ | 10 | CFLAGS_KASAN := $(call cc-option, -fsanitize=kernel-address \ |
| 11 | -fasan-shadow-offset=$(CONFIG_KASAN_SHADOW_OFFSET) \ | 11 | -fasan-shadow-offset=$(CONFIG_KASAN_SHADOW_OFFSET) \ |
| 12 | --param asan-stack=1 \ | 12 | --param asan-stack=1 --param asan-globals=1 \ |
| 13 | --param asan-instrumentation-with-call-threshold=$(call_threshold)) | 13 | --param asan-instrumentation-with-call-threshold=$(call_threshold)) |
| 14 | 14 | ||
| 15 | ifeq ($(call cc-option, $(CFLAGS_KASAN_MINIMAL) -Werror),) | 15 | ifeq ($(call cc-option, $(CFLAGS_KASAN_MINIMAL) -Werror),) |