kvm_s390_get_machine() populates the facility bitmap by copying bytes from the host results that are stored in a 256 byte array in the prefix page. The KVM code does use the size of the target buffer (2k), thus copying and exposing unrelated kernel memory (mostly machine check related logout data). Let's use the size of the source buffer instead. This is ok, as the target buffer will always be greater or equal than the source buffer as the KVM internal buffers (and thus S390_ARCH_FAC_LIST_SIZE_BYTE) cover the maximum possible size that is allowed by STFLE, which is 256 doublewords. All structures are zero allocated so we can leave bytes 256-2047 unchanged. Add a similar fix for kvm_arch_init_vm(). Reported-by: Heiko Carstens <heiko.carstens@xxxxxxxxxx> [found with smatch] Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx> CC: stable@xxxxxxxxxxxxxxx Acked-by: Cornelia Huck <cornelia.huck@xxxxxxxxxx> --- arch/s390/kvm/kvm-s390.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index bec71e9..6484a25 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -916,7 +916,7 @@ static int kvm_s390_get_machine(struct kvm *kvm, struct kvm_device_attr *attr) memcpy(&mach->fac_mask, kvm->arch.model.fac_mask, S390_ARCH_FAC_LIST_SIZE_BYTE); memcpy((unsigned long *)&mach->fac_list, S390_lowcore.stfle_fac_list, - S390_ARCH_FAC_LIST_SIZE_BYTE); + sizeof(S390_lowcore.stfle_fac_list)); if (copy_to_user((void __user *)attr->addr, mach, sizeof(*mach))) ret = -EFAULT; kfree(mach); @@ -1437,7 +1437,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) /* Populate the facility mask initially. */ memcpy(kvm->arch.model.fac_mask, S390_lowcore.stfle_fac_list, - S390_ARCH_FAC_LIST_SIZE_BYTE); + sizeof(S390_lowcore.stfle_fac_list)); for (i = 0; i < S390_ARCH_FAC_LIST_SIZE_U64; i++) { if (i < kvm_s390_fac_list_mask_size()) kvm->arch.model.fac_mask[i] &= kvm_s390_fac_list_mask[i]; -- 2.7.4