Commit fe8e3ee0 authored by Andy Shevchenko's avatar Andy Shevchenko Committed by Petr Mladek
Browse files

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: 50f530e1 ("lib: test_scanf: Add tests for sscanf number conversion")
Reported-by: default avatarkernel test robot <oliver.sang@intel.com>
Signed-off-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: default avatarRichard Fitzgerald <rf@opensource.cirrus.com>
Signed-off-by: default avatarPetr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20210727150132.28920-1-andriy.shevchenko@linux.intel.com
parent e563592c

lib/test_scanf.c

+2 −2
Original line number Diff line number Diff line
@@ -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)				\