Commit 00de073e authored by Nina Schoetterl-Glausch's avatar Nina Schoetterl-Glausch Committed by Janosch Frank
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KVM: s390: selftest: memop: Fix undefined behavior 



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: 0dd714bf ("KVM: s390: selftest: memop: Add cmpxchg tests")
Signed-off-by: default avatarNina Schoetterl-Glausch <nsg@linux.ibm.com>
Link: https://lore.kernel.org/r/20240111094805.363047-1-nsg@linux.ibm.com


Acked-by: default avatarJanosch Frank <frankja@linux.ibm.com>
Signed-off-by: default avatarJanosch Frank <frankja@linux.ibm.com>
Message-Id: <20240111094805.363047-1-nsg@linux.ibm.com>
parent 85a19b30

tools/testing/selftests/kvm/s390x/memop.c

+2 −0
Original line number Diff line number Diff line
@@ -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);

}