Messages in this thread Patch in this message | | | From | Andy Shevchenko <> | Subject | [PATCH v1 1/1] lib/test_scanf: Handle n_bits == 0 in random tests | Date | Tue, 27 Jul 2021 18:01:32 +0300 |
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UBSAN reported (via LKP)
[ 11.021349][ T1] UBSAN: shift-out-of-bounds in lib/test_scanf.c:275:51 [ 11.022782][ T1] shift exponent 32 is too large for 32-bit type 'unsigned int'
When n_bits == 0, the shift is out of range. Switch code to use GENMASK to handle this case.
Fixes: 50f530e176ea ("lib: test_scanf: Add tests for sscanf number conversion") Reported-by: kernel test robot <oliver.sang@intel.com> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> --- lib/test_scanf.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/lib/test_scanf.c b/lib/test_scanf.c index 84fe09eaf55e..abae88848972 100644 --- a/lib/test_scanf.c +++ b/lib/test_scanf.c @@ -271,7 +271,7 @@ static u32 __init next_test_random(u32 max_bits) { u32 n_bits = hweight32(prandom_u32_state(&rnd_state)) % (max_bits + 1); - return prandom_u32_state(&rnd_state) & (UINT_MAX >> (32 - n_bits)); + return prandom_u32_state(&rnd_state) & GENMASK(n_bits, 0); } static unsigned long long __init next_test_random_ull(void) @@ -280,7 +280,7 @@ static unsigned long long __init next_test_random_ull(void) u32 n_bits = (hweight32(rand1) * 3) % 64; u64 val = (u64)prandom_u32_state(&rnd_state) * rand1; - return val & (ULLONG_MAX >> (64 - n_bits)); + return val & GENMASK_ULL(n_bits, 0); } #define random_for_type(T) \ -- 2.30.2
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