| Message ID | 20240111094805.363047-1-nsg@linux.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] KVM: s390: selftest: memop: Fix undefined behavior | expand |
On 1/11/24 10:48, Nina Schoetterl-Glausch wrote: > 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 <nsg@linux.ibm.com> Acked-by: Janosch Frank <frankja@linux.ibm.com>
diff --git a/tools/testing/selftests/kvm/s390x/memop.c b/tools/testing/selftests/kvm/s390x/memop.c index bb3ca9a5d731..4ec8d0181e8d 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); }
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 <nsg@linux.ibm.com> --- v1 -> v2: use early return instead of modulus tools/testing/selftests/kvm/s390x/memop.c | 2 ++ 1 file changed, 2 insertions(+) base-commit: 305230142ae0637213bf6e04f6d9f10bbcb74af8