kernel/drivers/misc/lkdtm_refcount.c, branch linux-4.16.y

lkdtm: fix spelling mistake: "incremeted" -> "incremented"

2017-08-28T15:47:11Z

Trivial fix to spelling mistake in pr_info message Signed-off-by: Colin Ian King Acked-by: Kees Cook Signed-off-by: Greg Kroah-Hartman

lkdtm: Provide timing tests for atomic_t vs refcount_t

2017-07-26T21:38:04Z

While not a crash test, this does provide two tight atomic_t and refcount_t loops for performance comparisons: cd /sys/kernel/debug/provoke-crash perf stat -B -- cat <(echo ATOMIC_TIMING) > DIRECT perf stat -B -- cat <(echo REFCOUNT_TIMING) > DIRECT Looking a CPU cycles is the best way to example the fast-path (rather than instruction counts, since conditional jumps will be executed but will be negligible due to branch-prediction). Signed-off-by: Kees Cook

lkdtm: Provide more complete coverage for REFCOUNT tests

2017-07-26T21:38:03Z

The existing REFCOUNT_* LKDTM tests were designed only for testing a narrow portion of CONFIG_REFCOUNT_FULL. This moves the tests to their own file and expands their testing to poke each boundary condition. Since the protections (CONFIG_REFCOUNT_FULL and x86-fast) use different saturation values and reach-zero behavior, those have to be build-time set so the tests can actually validate things are happening at the right places. Notably, the x86-fast protection will fail REFCOUNT_INC_ZERO and REFCOUNT_ADD_ZERO since those conditions are not checked (only overflow is critical to protecting refcount_t). CONFIG_REFCOUNT_FULL will warn for each REFCOUNT_*_NEGATIVE test since it provides zero-pinning behaviors (which allows it to pass REFCOUNT_INC_ZERO and REFCOUNT_ADD_ZERO). Signed-off-by: Kees Cook