From fe8e3ee0d588566c1f44f28a555042ef50eba491 Mon Sep 17 00:00:00 2001 From: Andy Shevchenko Date: Tue, 27 Jul 2021 18:01:32 +0300 Subject: lib/test_scanf: Handle n_bits == 0 in random tests 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 Signed-off-by: Andy Shevchenko Reviewed-by: Richard Fitzgerald Signed-off-by: Petr Mladek Link: https://lore.kernel.org/r/20210727150132.28920-1-andriy.shevchenko@linux.intel.com --- lib/test_scanf.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'lib/test_scanf.c') diff --git a/lib/test_scanf.c b/lib/test_scanf.c index 48ff5747a4da..6a828dfc8ea1 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) \ -- cgit v1.2.3-59-g8ed1b