Rustam Kovhaev <rkovhaev@xxxxxxxxx> writes: > when kmalloc() fails in kvm_io_bus_unregister_dev(), before removing > the bus, we should iterate over all other devices linked to it and call > kvm_iodevice_destructor() for them > > Reported-and-tested-by: syzbot+f196caa45793d6374707@xxxxxxxxxxxxxxxxxxxxxxxxx > Link: https://syzkaller.appspot.com/bug?extid=f196caa45793d6374707 > Signed-off-by: Rustam Kovhaev <rkovhaev@xxxxxxxxx> > --- > virt/kvm/kvm_main.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index 67cd0b88a6b6..646aa7b82548 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -4332,7 +4332,7 @@ int kvm_io_bus_register_dev(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr, > void kvm_io_bus_unregister_dev(struct kvm *kvm, enum kvm_bus bus_idx, > struct kvm_io_device *dev) > { > - int i; > + int i, j; > struct kvm_io_bus *new_bus, *bus; > > bus = kvm_get_bus(kvm, bus_idx); > @@ -4351,6 +4351,11 @@ void kvm_io_bus_unregister_dev(struct kvm *kvm, enum kvm_bus bus_idx, > GFP_KERNEL_ACCOUNT); > if (!new_bus) { ^^^ redundant space > pr_err("kvm: failed to shrink bus, removing it completely\n"); > + for (j = 0; j < bus->dev_count; j++) { > + if (j == i) > + continue; > + kvm_iodevice_destructor(bus->range[j].dev); > + } > goto broken; The name of the label is really misleading (as it is not actually a failure path), I'd even suggest we get rid of this goto completely, something like new_bus = kmalloc(struct_size(bus, range, bus->dev_count - 1), GFP_KERNEL_ACCOUNT); if (new_bus) { memcpy(new_bus, bus, sizeof(*bus) + i * sizeof(struct kvm_io_range)); new_bus->dev_count--; memcpy(new_bus->range + i, bus->range + i + 1, (new_bus->dev_count - i) * sizeof(struct kvm_io_range)); } else { pr_err("kvm: failed to shrink bus, removing it completely\n"); for (j = 0; j < bus->dev_count; j++) { if (j == i) continue; kvm_iodevice_destructor(bus->range[j].dev); } rcu_assign_pointer(kvm->buses[bus_idx], new_bus); synchronize_srcu_expedited(&kvm->srcu); kfree(bus); return; > } None of the above should block the fix IMO, so: Reviewed-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> -- Vitaly
