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test_overflow: Add shift overflow tests
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This adds overflow tests for the new check_shift_overflow() helper to
validate overflow, signedness glitches, storage glitches, etc.

Co-developed-by: Rasmus Villemoes <[email protected]>
Signed-off-by: Kees Cook <[email protected]>
Signed-off-by: Jason Gunthorpe <[email protected]>
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@kees @jgunthorpe
kees authored and jgunthorpe committed Aug 8, 2018
1 parent 0c66847 commit d36b6ad
Showing 1 changed file with 197 additions and 1 deletion.
198 changes: 197 additions & 1 deletion lib/test_overflow.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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; \
Expand Down Expand Up @@ -287,6 +288,200 @@ 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_shl_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, 0, u8, 1 << 0, false);
err |= TEST_ONE_SHIFT(1, 4, u8, 1 << 4, false);
err |= TEST_ONE_SHIFT(1, 7, u8, 1 << 7, false);
err |= TEST_ONE_SHIFT(0xF, 4, u8, 0xF << 4, false);
err |= TEST_ONE_SHIFT(1, 0, u16, 1 << 0, 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(0xFF, 8, u16, 0xFF << 8, false);
err |= TEST_ONE_SHIFT(1, 0, int, 1 << 0, false);
err |= TEST_ONE_SHIFT(1, 16, int, 1 << 16, false);
err |= TEST_ONE_SHIFT(1, 30, int, 1 << 30, false);
err |= TEST_ONE_SHIFT(1, 0, s32, 1 << 0, false);
err |= TEST_ONE_SHIFT(1, 16, s32, 1 << 16, false);
err |= TEST_ONE_SHIFT(1, 30, s32, 1 << 30, false);
err |= TEST_ONE_SHIFT(1, 0, unsigned int, 1U << 0, 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(0xFFFFU, 16, unsigned int, 0xFFFFU << 16, false);
err |= TEST_ONE_SHIFT(1, 0, u32, 1U << 0, 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(0xFFFFU, 16, u32, 0xFFFFU << 16, false);
err |= TEST_ONE_SHIFT(1, 0, u64, 1ULL << 0, false);
err |= TEST_ONE_SHIFT(1, 40, u64, 1ULL << 40, false);
err |= TEST_ONE_SHIFT(1, 63, u64, 1ULL << 63, false);
err |= TEST_ONE_SHIFT(0xFFFFFFFFULL, 32, u64,
0xFFFFFFFFULL << 32, 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: shifted into the 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);

/* Overflow: high bit falls off unsigned types. */
/* 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);

/* Overflow: bit shifted into signed bit on signed types. */
/* 01001011 */
err |= TEST_ONE_SHIFT(75, 1, s8, 0, true);
/* 0100010001001011 */
err |= TEST_ONE_SHIFT(17483, 1, s16, 0, true);
/* 01000010000001000100010001001011 */
err |= TEST_ONE_SHIFT(1107575883, 1, s32, 0, true);
err |= TEST_ONE_SHIFT(1107575883, 1, int, 0, true);
/* 0100000100001000001000000010000001000010000001000100010001001011 */
err |= TEST_ONE_SHIFT(4686030735197619275LL, 1, s64, 0, true);

/* Overflow: bit shifted past signed bit on signed types. */
/* 01001011 */
err |= TEST_ONE_SHIFT(75, 2, s8, 0, true);
/* 0100010001001011 */
err |= TEST_ONE_SHIFT(17483, 2, s16, 0, true);
/* 01000010000001000100010001001011 */
err |= TEST_ONE_SHIFT(1107575883, 2, s32, 0, true);
err |= TEST_ONE_SHIFT(1107575883, 2, int, 0, true);
/* 0100000100001000001000000010000001000010000001000100010001001011 */
err |= TEST_ONE_SHIFT(4686030735197619275LL, 2, s64, 0, true);

/* Overflow: values larger than destination type. */
err |= TEST_ONE_SHIFT(0x100, 0, u8, 0, true);
err |= TEST_ONE_SHIFT(0xFF, 0, s8, 0, true);
err |= TEST_ONE_SHIFT(0x10000U, 0, u16, 0, true);
err |= TEST_ONE_SHIFT(0xFFFFU, 0, s16, 0, true);
err |= TEST_ONE_SHIFT(0x100000000ULL, 0, u32, 0, true);
err |= TEST_ONE_SHIFT(0x100000000ULL, 0, unsigned int, 0, true);
err |= TEST_ONE_SHIFT(0xFFFFFFFFUL, 0, s32, 0, true);
err |= TEST_ONE_SHIFT(0xFFFFFFFFUL, 0, int, 0, true);
err |= TEST_ONE_SHIFT(0xFFFFFFFFFFFFFFFFULL, 0, s64, 0, true);

/* Nonsense: negative initial value. */
err |= TEST_ONE_SHIFT(-1, 0, s8, 0, true);
err |= TEST_ONE_SHIFT(-1, 0, u8, 0, true);
err |= TEST_ONE_SHIFT(-5, 0, s16, 0, true);
err |= TEST_ONE_SHIFT(-5, 0, u16, 0, true);
err |= TEST_ONE_SHIFT(-10, 0, int, 0, true);
err |= TEST_ONE_SHIFT(-10, 0, unsigned int, 0, true);
err |= TEST_ONE_SHIFT(-100, 0, s32, 0, true);
err |= TEST_ONE_SHIFT(-100, 0, u32, 0, true);
err |= TEST_ONE_SHIFT(-10000, 0, s64, 0, true);
err |= TEST_ONE_SHIFT(-10000, 0, u64, 0, true);

/* Nonsense: negative shift values. */
err |= TEST_ONE_SHIFT(0, -5, s8, 0, true);
err |= TEST_ONE_SHIFT(0, -5, u8, 0, true);
err |= TEST_ONE_SHIFT(0, -10, s16, 0, true);
err |= TEST_ONE_SHIFT(0, -10, u16, 0, true);
err |= TEST_ONE_SHIFT(0, -15, int, 0, true);
err |= TEST_ONE_SHIFT(0, -15, unsigned int, 0, true);
err |= TEST_ONE_SHIFT(0, -20, s32, 0, true);
err |= TEST_ONE_SHIFT(0, -20, u32, 0, true);
err |= TEST_ONE_SHIFT(0, -30, s64, 0, true);
err |= TEST_ONE_SHIFT(0, -30, u64, 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);

/*
* 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".
Expand Down Expand Up @@ -397,6 +592,7 @@ static int __init test_module_init(void)
int err = 0;

err |= test_overflow_calculation();
err |= test_overflow_shift();
err |= test_overflow_allocation();

if (err) {
Expand Down

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