From 00de073e2420df02ac0f1a19dbfb60ff8eb198be Mon Sep 17 00:00:00 2001 From: Nina Schoetterl-Glausch Date: Thu, 11 Jan 2024 10:48:05 +0100 Subject: 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: 0dd714bfd200 ("KVM: s390: selftest: memop: Add cmpxchg tests") Signed-off-by: Nina Schoetterl-Glausch Link: https://lore.kernel.org/r/20240111094805.363047-1-nsg@linux.ibm.com Acked-by: Janosch Frank Signed-off-by: Janosch Frank Message-Id: <20240111094805.363047-1-nsg@linux.ibm.com> --- tools/testing/selftests/kvm/s390x/memop.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'tools') diff --git a/tools/testing/selftests/kvm/s390x/memop.c b/tools/testing/selftests/kvm/s390x/memop.c index bb3ca9a5d7318e..4ec8d0181e8db2 100644 --- a/tools/testing/selftests/kvm/s390x/memop.c +++ b/tools/testing/selftests/kvm/s390x/memop.c @@ -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); } -- cgit 1.2.3-korg