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KVM: s390: another fix for cmma migration
This fixes races and potential use after free in the cmma migration code. -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (GNU/Linux) iQIcBAABAgAGBQJaaJimAAoJEBF7vIC1phx8fIsP/1ShgCjg1Bcgc9FI/Rgo8diG oycjpv7BXp2dcrgW2FRB1LFoRpMoWAwOy4YNoMls/9gqemupYYa97F3viP3oVH56 wQaZjgRdpnvflmti+3S9Ca3aws7WUPuAONTld44TJZaVJXM8g52VtjPD5APMWFqL agawGopcmoxUX5qE12BAxCx1lx5/hToF5bcVULCmNogW9Cl9QOUw+8W3ezmaoJ0w 37FVyK5Xv+JvF8gXJlhLwXkcFyaEfLNUsoJdOCgi89/aULmp1z3/EmOTos3vTQwT 83lNxdjXuS+Ps4qGUnNwNTThoXhdC+rVbAZd/tbLi/8CtjvSeKqB0T8sMgvAC1Aa HXYgNbEtIxjdJYbWGbTy+8uCIHLgVMiYRnPymqa6j0Y8Tk07ji2g/r0kZNotykD6 Hb4CQ41MKAXljpLEXV1L1a/LKrfQBhlTIR4VCPy9GBN+4AgV+KzjF0l1N0B9r/RD sqSsttkbGNyNkPpCT+EGQa1d82on7T9lm40Ag6AAaBaw5x6lPwLAmDCslst5c3Fx pGmoJk6fe64saQcs49zOiPiBYrlawW69IIVJaHWWOG3z+EdgpMjvtn1XWJpkyPZq N0MDPn5+VwPRPQ3qKpaCRuVaUNn2gGuZSpx2/DsaY8gF65BLIIRjLt/SpLGxw3wU AUY13gafv82jM6xlpc0p =aAYd -----END PGP SIGNATURE----- Merge tag 'kvm-s390-master-4.15-3' of git://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux KVM: s390: another fix for cmma migration This fixes races and potential use after free in the cmma migration code.
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@ -769,7 +769,7 @@ static void kvm_s390_sync_request_broadcast(struct kvm *kvm, int req)
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/*
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* Must be called with kvm->srcu held to avoid races on memslots, and with
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* kvm->lock to avoid races with ourselves and kvm_s390_vm_stop_migration.
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* kvm->slots_lock to avoid races with ourselves and kvm_s390_vm_stop_migration.
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*/
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static int kvm_s390_vm_start_migration(struct kvm *kvm)
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{
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@ -825,7 +825,7 @@ static int kvm_s390_vm_start_migration(struct kvm *kvm)
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}
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/*
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* Must be called with kvm->lock to avoid races with ourselves and
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* Must be called with kvm->slots_lock to avoid races with ourselves and
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* kvm_s390_vm_start_migration.
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*/
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static int kvm_s390_vm_stop_migration(struct kvm *kvm)
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@ -840,6 +840,8 @@ static int kvm_s390_vm_stop_migration(struct kvm *kvm)
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if (kvm->arch.use_cmma) {
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kvm_s390_sync_request_broadcast(kvm, KVM_REQ_STOP_MIGRATION);
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/* We have to wait for the essa emulation to finish */
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synchronize_srcu(&kvm->srcu);
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vfree(mgs->pgste_bitmap);
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}
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kfree(mgs);
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@ -849,14 +851,12 @@ static int kvm_s390_vm_stop_migration(struct kvm *kvm)
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static int kvm_s390_vm_set_migration(struct kvm *kvm,
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struct kvm_device_attr *attr)
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{
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int idx, res = -ENXIO;
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int res = -ENXIO;
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mutex_lock(&kvm->lock);
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mutex_lock(&kvm->slots_lock);
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switch (attr->attr) {
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case KVM_S390_VM_MIGRATION_START:
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idx = srcu_read_lock(&kvm->srcu);
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res = kvm_s390_vm_start_migration(kvm);
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srcu_read_unlock(&kvm->srcu, idx);
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break;
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case KVM_S390_VM_MIGRATION_STOP:
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res = kvm_s390_vm_stop_migration(kvm);
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@ -864,7 +864,7 @@ static int kvm_s390_vm_set_migration(struct kvm *kvm,
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default:
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break;
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}
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mutex_unlock(&kvm->lock);
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mutex_unlock(&kvm->slots_lock);
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return res;
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}
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@ -1754,7 +1754,9 @@ long kvm_arch_vm_ioctl(struct file *filp,
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r = -EFAULT;
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if (copy_from_user(&args, argp, sizeof(args)))
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break;
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mutex_lock(&kvm->slots_lock);
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r = kvm_s390_get_cmma_bits(kvm, &args);
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mutex_unlock(&kvm->slots_lock);
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if (!r) {
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r = copy_to_user(argp, &args, sizeof(args));
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if (r)
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@ -1768,7 +1770,9 @@ long kvm_arch_vm_ioctl(struct file *filp,
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r = -EFAULT;
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if (copy_from_user(&args, argp, sizeof(args)))
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break;
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mutex_lock(&kvm->slots_lock);
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r = kvm_s390_set_cmma_bits(kvm, &args);
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mutex_unlock(&kvm->slots_lock);
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break;
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}
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default:
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