This adds overflow tests for the new check_shift_overflow() helper to
validate overflow, signedness glitches, storage glitches, etc.
Co-developed-by: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
lib/test_overflow.c | 140 +++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 139 insertions(+), 1 deletion(-)
diff --git a/lib/test_overflow.c b/lib/test_overflow.c
index 2278fe05a1b0..face66e8aa37 100644
--- a/lib/test_overflow.c
+++ b/lib/test_overflow.c
@@ -252,7 +252,8 @@ static int __init test_ ## t ## _overflow(void) { \
int err = 0; \
unsigned i; \
\
- pr_info("%-3s: %zu tests\n", #t, ARRAY_SIZE(t ## _tests)); \
+ pr_info("%-3s: %zu arithmetic tests\n", #t, \
+ ARRAY_SIZE(t ## _tests)); \
for (i = 0; i < ARRAY_SIZE(t ## _tests); ++i) \
err |= do_test_ ## t(&t ## _tests[i]); \
return err; \
@@ -287,6 +288,142 @@ static int __init test_overflow_calculation(void)
return err;
}
+static int __init test_overflow_shift(void)
+{
+ int err = 0;
+
+/* Args are: value, shift, type, expected result, overflow expected */
+#define TEST_ONE_SHIFT(a, s, t, expect, of) ({ \
+ int __failed = 0; \
+ typeof(a) __a = (a); \
+ typeof(s) __s = (s); \
+ t __e = (expect); \
+ t __d; \
+ bool __of = check_shift_overflow(__a, __s, &__d); \
+ if (__of != of) { \
+ pr_warn("expected (%s)(%s << %s) to%s overflow\n", \
+ #t, #a, #s, of ? "" : " not"); \
+ __failed = 1; \
+ } else if (!__of && __d != __e) { \
+ pr_warn("expected (%s)(%s << %s) == %s\n", \
+ #t, #a, #s, #expect); \
+ if ((t)-1 < 0) \
+ pr_warn("got %lld\n", (s64)__d); \
+ else \
+ pr_warn("got %llu\n", (u64)__d); \
+ __failed = 1; \
+ } \
+ if (!__failed) \
+ pr_info("ok: (%s)(%s << %s) == %s\n", #t, #a, #s, \
+ of ? "overflow" : #expect); \
+ __failed; \
+})
+
+ /* Sane shifts */
+ err |= TEST_ONE_SHIFT(1, 4, u8, 1 << 4, false);
+ err |= TEST_ONE_SHIFT(1, 7, u8, 1 << 7, false);
+ err |= TEST_ONE_SHIFT(1, 10, u16, 1 << 10, false);
+ err |= TEST_ONE_SHIFT(1, 15, u16, 1 << 15, false);
+ err |= TEST_ONE_SHIFT(1, 30, int, 1 << 30, false);
+ err |= TEST_ONE_SHIFT(1, 30, s32, 1 << 30, false);
+ err |= TEST_ONE_SHIFT(1, 20, unsigned int, 1U << 20, false);
+ err |= TEST_ONE_SHIFT(1, 31, unsigned int, 1U << 31, false);
+ err |= TEST_ONE_SHIFT(1, 20, u32, 1U << 20, false);
+ err |= TEST_ONE_SHIFT(1, 31, u32, 1U << 31, false);
+ err |= TEST_ONE_SHIFT(1, 40, u64, 1ULL << 40, false);
+ err |= TEST_ONE_SHIFT(1, 63, u64, 1ULL << 63, false);
+
+ /* Sane shift: start and end with 0, without a too-wide shift. */
+ err |= TEST_ONE_SHIFT(0, 7, u8, 0, false);
+ err |= TEST_ONE_SHIFT(0, 15, u16, 0, false);
+ err |= TEST_ONE_SHIFT(0, 31, unsigned int, 0, false);
+ err |= TEST_ONE_SHIFT(0, 31, u32, 0, false);
+ err |= TEST_ONE_SHIFT(0, 63, u64, 0, false);
+
+ /* Sane shift: start and end with 0, without reaching signed bit. */
+ err |= TEST_ONE_SHIFT(0, 6, s8, 0, false);
+ err |= TEST_ONE_SHIFT(0, 14, s16, 0, false);
+ err |= TEST_ONE_SHIFT(0, 30, int, 0, false);
+ err |= TEST_ONE_SHIFT(0, 30, s32, 0, false);
+ err |= TEST_ONE_SHIFT(0, 62, s64, 0, false);
+
+ /* Overflow: shifted the bit off the end. */
+ err |= TEST_ONE_SHIFT(1, 8, u8, 0, true);
+ err |= TEST_ONE_SHIFT(1, 16, u16, 0, true);
+ err |= TEST_ONE_SHIFT(1, 32, unsigned int, 0, true);
+ err |= TEST_ONE_SHIFT(1, 32, u32, 0, true);
+ err |= TEST_ONE_SHIFT(1, 64, u64, 0, true);
+
+ /* Overflow: high bit falls off. */
+ /* 10010110 */
+ err |= TEST_ONE_SHIFT(150, 1, u8, 0, true);
+ /* 1000100010010110 */
+ err |= TEST_ONE_SHIFT(34966, 1, u16, 0, true);
+ /* 10000100000010001000100010010110 */
+ err |= TEST_ONE_SHIFT(2215151766U, 1, u32, 0, true);
+ err |= TEST_ONE_SHIFT(2215151766U, 1, unsigned int, 0, true);
+ /* 1000001000010000010000000100000010000100000010001000100010010110 */
+ err |= TEST_ONE_SHIFT(9372061470395238550ULL, 1, u64, 0, true);
+
+ /* Nonsense: negative initial value. */
+ err |= TEST_ONE_SHIFT(-1, 0, s8, 0, true);
+ err |= TEST_ONE_SHIFT(-5, 0, s16, 0, true);
+ err |= TEST_ONE_SHIFT(-10, 0, int, 0, true);
+ err |= TEST_ONE_SHIFT(-100, 0, s32, 0, true);
+ err |= TEST_ONE_SHIFT(-10000, 0, s64, 0, true);
+
+ /* Nonsense: negative shift values. */
+ err |= TEST_ONE_SHIFT(0, -5, s8, 0, true);
+ err |= TEST_ONE_SHIFT(0, -10, s16, 0, true);
+ err |= TEST_ONE_SHIFT(0, -15, int, 0, true);
+ err |= TEST_ONE_SHIFT(0, -20, s32, 0, true);
+ err |= TEST_ONE_SHIFT(0, -30, s64, 0, true);
+
+ /* Overflow: shifted at or beyond entire type's bit width. */
+ err |= TEST_ONE_SHIFT(0, 8, u8, 0, true);
+ err |= TEST_ONE_SHIFT(0, 9, u8, 0, true);
+ err |= TEST_ONE_SHIFT(0, 8, s8, 0, true);
+ err |= TEST_ONE_SHIFT(0, 9, s8, 0, true);
+ err |= TEST_ONE_SHIFT(0, 16, u16, 0, true);
+ err |= TEST_ONE_SHIFT(0, 17, u16, 0, true);
+ err |= TEST_ONE_SHIFT(0, 16, s16, 0, true);
+ err |= TEST_ONE_SHIFT(0, 17, s16, 0, true);
+ err |= TEST_ONE_SHIFT(0, 32, u32, 0, true);
+ err |= TEST_ONE_SHIFT(0, 33, u32, 0, true);
+ err |= TEST_ONE_SHIFT(0, 32, int, 0, true);
+ err |= TEST_ONE_SHIFT(0, 33, int, 0, true);
+ err |= TEST_ONE_SHIFT(0, 32, s32, 0, true);
+ err |= TEST_ONE_SHIFT(0, 33, s32, 0, true);
+ err |= TEST_ONE_SHIFT(0, 64, u64, 0, true);
+ err |= TEST_ONE_SHIFT(0, 65, u64, 0, true);
+ err |= TEST_ONE_SHIFT(0, 64, s64, 0, true);
+ err |= TEST_ONE_SHIFT(0, 65, s64, 0, true);
+
+ /* Overflow: shifted into signed bit. */
+ err |= TEST_ONE_SHIFT(1, 7, s8, 0, true);
+ err |= TEST_ONE_SHIFT(1, 15, s16, 0, true);
+ err |= TEST_ONE_SHIFT(1, 31, int, 0, true);
+ err |= TEST_ONE_SHIFT(1, 31, s32, 0, true);
+ err |= TEST_ONE_SHIFT(1, 63, s64, 0, true);
+
+ /*
+ * Corner case: for unsigned types, we fail when we've shifted
+ * through the entire width of bits. For signed types, we might
+ * want to match this behavior, but that would mean noticing if
+ * we shift through all but the signed bit, and this is not
+ * currently detected (but we'll notice an overflow into the
+ * signed bit). So, for now, we will test this condition but
+ * mark it as not expected to overflow.
+ */
+ err |= TEST_ONE_SHIFT(0, 7, s8, 0, false);
+ err |= TEST_ONE_SHIFT(0, 15, s16, 0, false);
+ err |= TEST_ONE_SHIFT(0, 31, int, 0, false);
+ err |= TEST_ONE_SHIFT(0, 31, s32, 0, false);
+ err |= TEST_ONE_SHIFT(0, 63, s64, 0, false);
+
+ return err;
+}
+
/*
* Deal with the various forms of allocator arguments. See comments above
* the DEFINE_TEST_ALLOC() instances for mapping of the "bits".
@@ -397,6 +534,7 @@ static int __init test_module_init(void)
int err = 0;
err |= test_overflow_calculation();
+ err |= test_overflow_shift();
err |= test_overflow_allocation();
if (err) {
--
2.17.1
--
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