For reasons I cannot understand, m68k moves the start of the stack frame for consecutive calls to the same function if the function's test variable is larger than 8 bytes. This was only happening for the char array test (obviously), so adjust the length of the string for m68k only. I want the array size to be longer than "unsigned long" for every given architecture, so the other remain unchanged.
Additionally adjust the error message to be a bit more clear about what's happened, and move the KUNIT check outside of the consecutive calls to minimize what happens between them. Reported-by: Guenter Roeck <li...@roeck-us.net> Closes: https://lore.kernel.org/lkml/a0d10d50-2720-4ecd-a2c6-c2c5e5aee...@roeck-us.net/ Signed-off-by: Kees Cook <keesc...@chromium.org> --- Cc: Geert Uytterhoeven <ge...@linux-m68k.org> --- lib/stackinit_kunit.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) diff --git a/lib/stackinit_kunit.c b/lib/stackinit_kunit.c index 05947a2feb93..dc3c68f46f0a 100644 --- a/lib/stackinit_kunit.c +++ b/lib/stackinit_kunit.c @@ -63,7 +63,16 @@ static bool stackinit_range_contains(char *haystack_start, size_t haystack_size, #define FETCH_ARG_STRING(var) var #define FETCH_ARG_STRUCT(var) &var +/* + * On m68k, if the leaf function test variable is longer than 8 bytes, + * the start of the stack frame moves. 8 is sufficiently large to + * test m68k char arrays, but leave it at 16 for other architectures. + */ +#ifdef CONFIG_M68K +#define FILL_SIZE_STRING 8 +#else #define FILL_SIZE_STRING 16 +#endif #define INIT_CLONE_SCALAR /**/ #define INIT_CLONE_STRING [FILL_SIZE_STRING] @@ -165,19 +174,23 @@ static noinline void test_ ## name (struct kunit *test) \ /* Verify all bytes overwritten with 0xFF. */ \ for (sum = 0, i = 0; i < target_size; i++) \ sum += (check_buf[i] != 0xFF); \ - KUNIT_ASSERT_EQ_MSG(test, sum, 0, \ - "leaf fill was not 0xFF!?\n"); \ /* Clear entire check buffer for later bit tests. */ \ memset(check_buf, 0x00, sizeof(check_buf)); \ /* Extract stack-defined variable contents. */ \ ignored = leaf_ ##name((unsigned long)&ignored, 0, \ FETCH_ARG_ ## which(zero)); \ + /* \ + * Delay the sum test to here to do as little as \ + * possible between the two leaf function calls. \ + */ \ + KUNIT_ASSERT_EQ_MSG(test, sum, 0, \ + "leaf fill was not 0xFF!?\n"); \ \ /* Validate that compiler lined up fill and target. */ \ KUNIT_ASSERT_TRUE_MSG(test, \ stackinit_range_contains(fill_start, fill_size, \ target_start, target_size), \ - "stack fill missed target!? " \ + "stackframe was not the same between calls!? " \ "(fill %zu wide, target offset by %d)\n", \ fill_size, \ (int)((ssize_t)(uintptr_t)fill_start - \ -- 2.34.1
