diff options
author | Sami Tolvanen <samitolvanen@google.com> | 2022-09-09 00:54:49 +0300 |
---|---|---|
committer | Kees Cook <keescook@chromium.org> | 2022-09-26 20:13:13 +0300 |
commit | cf90d0383560de12330de8cf3f831b14cdd45914 (patch) | |
tree | ea2f1c5f4a7c85f6b7a11a247adfce46243af254 /drivers/misc/lkdtm | |
parent | e84e008e7b02c015047e76261726da1550130a59 (diff) | |
download | linux-cf90d0383560de12330de8cf3f831b14cdd45914.tar.xz |
lkdtm: Emit an indirect call for CFI tests
Clang can convert the indirect calls in lkdtm_CFI_FORWARD_PROTO into
direct calls. Move the call into a noinline function that accepts the
target address as an argument to ensure the compiler actually emits an
indirect call instead.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Kees Cook <keescook@chromium.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220908215504.3686827-8-samitolvanen@google.com
Diffstat (limited to 'drivers/misc/lkdtm')
-rw-r--r-- | drivers/misc/lkdtm/cfi.c | 15 |
1 files changed, 9 insertions, 6 deletions
diff --git a/drivers/misc/lkdtm/cfi.c b/drivers/misc/lkdtm/cfi.c index 71483cb1e422..5245cf6013c9 100644 --- a/drivers/misc/lkdtm/cfi.c +++ b/drivers/misc/lkdtm/cfi.c @@ -20,6 +20,13 @@ static noinline int lkdtm_increment_int(int *counter) return *counter; } + +/* Don't allow the compiler to inline the calls. */ +static noinline void lkdtm_indirect_call(void (*func)(int *)) +{ + func(&called_count); +} + /* * This tries to call an indirect function with a mismatched prototype. */ @@ -29,15 +36,11 @@ static void lkdtm_CFI_FORWARD_PROTO(void) * Matches lkdtm_increment_void()'s prototype, but not * lkdtm_increment_int()'s prototype. */ - void (*func)(int *); - pr_info("Calling matched prototype ...\n"); - func = lkdtm_increment_void; - func(&called_count); + lkdtm_indirect_call(lkdtm_increment_void); pr_info("Calling mismatched prototype ...\n"); - func = (void *)lkdtm_increment_int; - func(&called_count); + lkdtm_indirect_call((void *)lkdtm_increment_int); pr_err("FAIL: survived mismatched prototype function call!\n"); pr_expected_config(CONFIG_CFI_CLANG); |