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test_overflow: Add shift overflow tests
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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‎lib/test_overflow.c

Lines changed: 197 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -252,7 +252,8 @@ static int __init test_ ## t ## _overflow(void) { \
252252
int err = 0; \
253253
unsigned i; \
254254
\
255-
pr_info("%-3s: %zu tests\n", #t, ARRAY_SIZE(t ## _tests)); \
255+
pr_info("%-3s: %zu arithmetic tests\n", #t, \
256+
ARRAY_SIZE(t ## _tests)); \
256257
for (i = 0; i < ARRAY_SIZE(t ## _tests); ++i) \
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err |= do_test_ ## t(&t ## _tests[i]); \
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return err; \
@@ -287,6 +288,200 @@ static int __init test_overflow_calculation(void)
287288
return err;
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}
289290

291+
static int __init test_overflow_shift(void)
292+
{
293+
int err = 0;
294+
295+
/* Args are: value, shift, type, expected result, overflow expected */
296+
#define TEST_ONE_SHIFT(a, s, t, expect, of) ({ \
297+
int __failed = 0; \
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typeof(a) __a = (a); \
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typeof(s) __s = (s); \
300+
t __e = (expect); \
301+
t __d; \
302+
bool __of = check_shl_overflow(__a, __s, &__d); \
303+
if (__of != of) { \
304+
pr_warn("expected (%s)(%s << %s) to%s overflow\n", \
305+
#t, #a, #s, of ? "" : " not"); \
306+
__failed = 1; \
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} else if (!__of && __d != __e) { \
308+
pr_warn("expected (%s)(%s << %s) == %s\n", \
309+
#t, #a, #s, #expect); \
310+
if ((t)-1 < 0) \
311+
pr_warn("got %lld\n", (s64)__d); \
312+
else \
313+
pr_warn("got %llu\n", (u64)__d); \
314+
__failed = 1; \
315+
} \
316+
if (!__failed) \
317+
pr_info("ok: (%s)(%s << %s) == %s\n", #t, #a, #s, \
318+
of ? "overflow" : #expect); \
319+
__failed; \
320+
})
321+
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/* Sane shifts. */
323+
err |= TEST_ONE_SHIFT(1, 0, u8, 1 << 0, false);
324+
err |= TEST_ONE_SHIFT(1, 4, u8, 1 << 4, false);
325+
err |= TEST_ONE_SHIFT(1, 7, u8, 1 << 7, false);
326+
err |= TEST_ONE_SHIFT(0xF, 4, u8, 0xF << 4, false);
327+
err |= TEST_ONE_SHIFT(1, 0, u16, 1 << 0, false);
328+
err |= TEST_ONE_SHIFT(1, 10, u16, 1 << 10, false);
329+
err |= TEST_ONE_SHIFT(1, 15, u16, 1 << 15, false);
330+
err |= TEST_ONE_SHIFT(0xFF, 8, u16, 0xFF << 8, false);
331+
err |= TEST_ONE_SHIFT(1, 0, int, 1 << 0, false);
332+
err |= TEST_ONE_SHIFT(1, 16, int, 1 << 16, false);
333+
err |= TEST_ONE_SHIFT(1, 30, int, 1 << 30, false);
334+
err |= TEST_ONE_SHIFT(1, 0, s32, 1 << 0, false);
335+
err |= TEST_ONE_SHIFT(1, 16, s32, 1 << 16, false);
336+
err |= TEST_ONE_SHIFT(1, 30, s32, 1 << 30, false);
337+
err |= TEST_ONE_SHIFT(1, 0, unsigned int, 1U << 0, false);
338+
err |= TEST_ONE_SHIFT(1, 20, unsigned int, 1U << 20, false);
339+
err |= TEST_ONE_SHIFT(1, 31, unsigned int, 1U << 31, false);
340+
err |= TEST_ONE_SHIFT(0xFFFFU, 16, unsigned int, 0xFFFFU << 16, false);
341+
err |= TEST_ONE_SHIFT(1, 0, u32, 1U << 0, false);
342+
err |= TEST_ONE_SHIFT(1, 20, u32, 1U << 20, false);
343+
err |= TEST_ONE_SHIFT(1, 31, u32, 1U << 31, false);
344+
err |= TEST_ONE_SHIFT(0xFFFFU, 16, u32, 0xFFFFU << 16, false);
345+
err |= TEST_ONE_SHIFT(1, 0, u64, 1ULL << 0, false);
346+
err |= TEST_ONE_SHIFT(1, 40, u64, 1ULL << 40, false);
347+
err |= TEST_ONE_SHIFT(1, 63, u64, 1ULL << 63, false);
348+
err |= TEST_ONE_SHIFT(0xFFFFFFFFULL, 32, u64,
349+
0xFFFFFFFFULL << 32, false);
350+
351+
/* Sane shift: start and end with 0, without a too-wide shift. */
352+
err |= TEST_ONE_SHIFT(0, 7, u8, 0, false);
353+
err |= TEST_ONE_SHIFT(0, 15, u16, 0, false);
354+
err |= TEST_ONE_SHIFT(0, 31, unsigned int, 0, false);
355+
err |= TEST_ONE_SHIFT(0, 31, u32, 0, false);
356+
err |= TEST_ONE_SHIFT(0, 63, u64, 0, false);
357+
358+
/* Sane shift: start and end with 0, without reaching signed bit. */
359+
err |= TEST_ONE_SHIFT(0, 6, s8, 0, false);
360+
err |= TEST_ONE_SHIFT(0, 14, s16, 0, false);
361+
err |= TEST_ONE_SHIFT(0, 30, int, 0, false);
362+
err |= TEST_ONE_SHIFT(0, 30, s32, 0, false);
363+
err |= TEST_ONE_SHIFT(0, 62, s64, 0, false);
364+
365+
/* Overflow: shifted the bit off the end. */
366+
err |= TEST_ONE_SHIFT(1, 8, u8, 0, true);
367+
err |= TEST_ONE_SHIFT(1, 16, u16, 0, true);
368+
err |= TEST_ONE_SHIFT(1, 32, unsigned int, 0, true);
369+
err |= TEST_ONE_SHIFT(1, 32, u32, 0, true);
370+
err |= TEST_ONE_SHIFT(1, 64, u64, 0, true);
371+
372+
/* Overflow: shifted into the signed bit. */
373+
err |= TEST_ONE_SHIFT(1, 7, s8, 0, true);
374+
err |= TEST_ONE_SHIFT(1, 15, s16, 0, true);
375+
err |= TEST_ONE_SHIFT(1, 31, int, 0, true);
376+
err |= TEST_ONE_SHIFT(1, 31, s32, 0, true);
377+
err |= TEST_ONE_SHIFT(1, 63, s64, 0, true);
378+
379+
/* Overflow: high bit falls off unsigned types. */
380+
/* 10010110 */
381+
err |= TEST_ONE_SHIFT(150, 1, u8, 0, true);
382+
/* 1000100010010110 */
383+
err |= TEST_ONE_SHIFT(34966, 1, u16, 0, true);
384+
/* 10000100000010001000100010010110 */
385+
err |= TEST_ONE_SHIFT(2215151766U, 1, u32, 0, true);
386+
err |= TEST_ONE_SHIFT(2215151766U, 1, unsigned int, 0, true);
387+
/* 1000001000010000010000000100000010000100000010001000100010010110 */
388+
err |= TEST_ONE_SHIFT(9372061470395238550ULL, 1, u64, 0, true);
389+
390+
/* Overflow: bit shifted into signed bit on signed types. */
391+
/* 01001011 */
392+
err |= TEST_ONE_SHIFT(75, 1, s8, 0, true);
393+
/* 0100010001001011 */
394+
err |= TEST_ONE_SHIFT(17483, 1, s16, 0, true);
395+
/* 01000010000001000100010001001011 */
396+
err |= TEST_ONE_SHIFT(1107575883, 1, s32, 0, true);
397+
err |= TEST_ONE_SHIFT(1107575883, 1, int, 0, true);
398+
/* 0100000100001000001000000010000001000010000001000100010001001011 */
399+
err |= TEST_ONE_SHIFT(4686030735197619275LL, 1, s64, 0, true);
400+
401+
/* Overflow: bit shifted past signed bit on signed types. */
402+
/* 01001011 */
403+
err |= TEST_ONE_SHIFT(75, 2, s8, 0, true);
404+
/* 0100010001001011 */
405+
err |= TEST_ONE_SHIFT(17483, 2, s16, 0, true);
406+
/* 01000010000001000100010001001011 */
407+
err |= TEST_ONE_SHIFT(1107575883, 2, s32, 0, true);
408+
err |= TEST_ONE_SHIFT(1107575883, 2, int, 0, true);
409+
/* 0100000100001000001000000010000001000010000001000100010001001011 */
410+
err |= TEST_ONE_SHIFT(4686030735197619275LL, 2, s64, 0, true);
411+
412+
/* Overflow: values larger than destination type. */
413+
err |= TEST_ONE_SHIFT(0x100, 0, u8, 0, true);
414+
err |= TEST_ONE_SHIFT(0xFF, 0, s8, 0, true);
415+
err |= TEST_ONE_SHIFT(0x10000U, 0, u16, 0, true);
416+
err |= TEST_ONE_SHIFT(0xFFFFU, 0, s16, 0, true);
417+
err |= TEST_ONE_SHIFT(0x100000000ULL, 0, u32, 0, true);
418+
err |= TEST_ONE_SHIFT(0x100000000ULL, 0, unsigned int, 0, true);
419+
err |= TEST_ONE_SHIFT(0xFFFFFFFFUL, 0, s32, 0, true);
420+
err |= TEST_ONE_SHIFT(0xFFFFFFFFUL, 0, int, 0, true);
421+
err |= TEST_ONE_SHIFT(0xFFFFFFFFFFFFFFFFULL, 0, s64, 0, true);
422+
423+
/* Nonsense: negative initial value. */
424+
err |= TEST_ONE_SHIFT(-1, 0, s8, 0, true);
425+
err |= TEST_ONE_SHIFT(-1, 0, u8, 0, true);
426+
err |= TEST_ONE_SHIFT(-5, 0, s16, 0, true);
427+
err |= TEST_ONE_SHIFT(-5, 0, u16, 0, true);
428+
err |= TEST_ONE_SHIFT(-10, 0, int, 0, true);
429+
err |= TEST_ONE_SHIFT(-10, 0, unsigned int, 0, true);
430+
err |= TEST_ONE_SHIFT(-100, 0, s32, 0, true);
431+
err |= TEST_ONE_SHIFT(-100, 0, u32, 0, true);
432+
err |= TEST_ONE_SHIFT(-10000, 0, s64, 0, true);
433+
err |= TEST_ONE_SHIFT(-10000, 0, u64, 0, true);
434+
435+
/* Nonsense: negative shift values. */
436+
err |= TEST_ONE_SHIFT(0, -5, s8, 0, true);
437+
err |= TEST_ONE_SHIFT(0, -5, u8, 0, true);
438+
err |= TEST_ONE_SHIFT(0, -10, s16, 0, true);
439+
err |= TEST_ONE_SHIFT(0, -10, u16, 0, true);
440+
err |= TEST_ONE_SHIFT(0, -15, int, 0, true);
441+
err |= TEST_ONE_SHIFT(0, -15, unsigned int, 0, true);
442+
err |= TEST_ONE_SHIFT(0, -20, s32, 0, true);
443+
err |= TEST_ONE_SHIFT(0, -20, u32, 0, true);
444+
err |= TEST_ONE_SHIFT(0, -30, s64, 0, true);
445+
err |= TEST_ONE_SHIFT(0, -30, u64, 0, true);
446+
447+
/* Overflow: shifted at or beyond entire type's bit width. */
448+
err |= TEST_ONE_SHIFT(0, 8, u8, 0, true);
449+
err |= TEST_ONE_SHIFT(0, 9, u8, 0, true);
450+
err |= TEST_ONE_SHIFT(0, 8, s8, 0, true);
451+
err |= TEST_ONE_SHIFT(0, 9, s8, 0, true);
452+
err |= TEST_ONE_SHIFT(0, 16, u16, 0, true);
453+
err |= TEST_ONE_SHIFT(0, 17, u16, 0, true);
454+
err |= TEST_ONE_SHIFT(0, 16, s16, 0, true);
455+
err |= TEST_ONE_SHIFT(0, 17, s16, 0, true);
456+
err |= TEST_ONE_SHIFT(0, 32, u32, 0, true);
457+
err |= TEST_ONE_SHIFT(0, 33, u32, 0, true);
458+
err |= TEST_ONE_SHIFT(0, 32, int, 0, true);
459+
err |= TEST_ONE_SHIFT(0, 33, int, 0, true);
460+
err |= TEST_ONE_SHIFT(0, 32, s32, 0, true);
461+
err |= TEST_ONE_SHIFT(0, 33, s32, 0, true);
462+
err |= TEST_ONE_SHIFT(0, 64, u64, 0, true);
463+
err |= TEST_ONE_SHIFT(0, 65, u64, 0, true);
464+
err |= TEST_ONE_SHIFT(0, 64, s64, 0, true);
465+
err |= TEST_ONE_SHIFT(0, 65, s64, 0, true);
466+
467+
/*
468+
* Corner case: for unsigned types, we fail when we've shifted
469+
* through the entire width of bits. For signed types, we might
470+
* want to match this behavior, but that would mean noticing if
471+
* we shift through all but the signed bit, and this is not
472+
* currently detected (but we'll notice an overflow into the
473+
* signed bit). So, for now, we will test this condition but
474+
* mark it as not expected to overflow.
475+
*/
476+
err |= TEST_ONE_SHIFT(0, 7, s8, 0, false);
477+
err |= TEST_ONE_SHIFT(0, 15, s16, 0, false);
478+
err |= TEST_ONE_SHIFT(0, 31, int, 0, false);
479+
err |= TEST_ONE_SHIFT(0, 31, s32, 0, false);
480+
err |= TEST_ONE_SHIFT(0, 63, s64, 0, false);
481+
482+
return err;
483+
}
484+
290485
/*
291486
* Deal with the various forms of allocator arguments. See comments above
292487
* the DEFINE_TEST_ALLOC() instances for mapping of the "bits".
@@ -397,6 +592,7 @@ static int __init test_module_init(void)
397592
int err = 0;
398593

399594
err |= test_overflow_calculation();
595+
err |= test_overflow_shift();
400596
err |= test_overflow_allocation();
401597

402598
if (err) {

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