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KVM: s390: selftest: memop: Fix undefined behavior

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If an integer's type has x bits, shifting the integer left by x or more
is undefined behavior.
This can happen in the rotate function when attempting to do a rotation
of the whole value by 0.

Fixes: 0dd714bfd2 ("KVM: s390: selftest: memop: Add cmpxchg tests")
Signed-off-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Link: https://lore.kernel.org/r/20240111094805.363047-1-nsg@linux.ibm.com
Acked-by: Janosch Frank <frankja@linux.ibm.com>
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Message-Id: <20240111094805.363047-1-nsg@linux.ibm.com>
This commit is contained in:
Nina Schoetterl-Glausch 2024-01-11 10:48:05 +01:00 committed by Janosch Frank
parent 85a19b3054
commit 00de073e24
1 changed files with 2 additions and 0 deletions
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2
tools/testing/selftests/kvm/s390x/memop.c
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@ -489,6 +489,8 @@ static __uint128_t rotate(int size, __uint128_t val, int amount)
amount = (amount + bits) % bits;
val = cut_to_size(size, val);
if (!amount)
return val;
return (val << (bits - amount)) | (val >> amount);
}