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Both shifts > in the rounding expression then exceed the width of u64. UBSAN reports a > shift exponent of 149, and the conversion can return a nonzero reading. > > Return zero when the required right shift is at least 64 bits. With the > supported precisions, the scaled mantissa is too small to round up in > this case. > > Fixes: 4cdb56214746 ("hwmon: lochnagar: Add Lochnagar 2 hardware monitoring driver") > Signed-off-by: Zhu Jun Thanks for adding the sign off. > + else if (exp <= -64) > + result = 0; > else if (exp < 0) > result = (man + (1ull << (-exp - 1))) >> -exp; But as I missed and Guenter Roeck kindly pointed out there is no value in this. The shift in the following case will just result in a value of zero anyway. Thanks, Charles