Hi, On 9/2/20 17:57, Rustam Kovhaev wrote: > 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> > Reviewed-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> I think it's worthwhile to add a Fixes tag for this, too. Please, see more comments below... > --- > v2: > - remove redundant whitespace > - remove goto statement and use if/else > --- > virt/kvm/kvm_main.c | 21 ++++++++++++--------- > 1 file changed, 12 insertions(+), 9 deletions(-) > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index 67cd0b88a6b6..cf88233b819a 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); > @@ -4349,17 +4349,20 @@ void kvm_io_bus_unregister_dev(struct kvm *kvm, enum kvm_bus bus_idx, > > new_bus = kmalloc(struct_size(bus, range, bus->dev_count - 1), > GFP_KERNEL_ACCOUNT); > - if (!new_bus) { > + if (new_bus) { > + memcpy(new_bus, bus, sizeof(*bus) + i * sizeof(struct kvm_io_range)); ^^^ It seems that you can use struct_size() here (see the allocation code above)... > + new_bus->dev_count--; > + memcpy(new_bus->range + i, bus->range + i + 1, > + (new_bus->dev_count - i) * sizeof(struct kvm_io_range)); ^^^ ...and, if possible, you can also use flex_array_size() here. Thanks -- Gustavo > + } else { > pr_err("kvm: failed to shrink bus, removing it completely\n"); > - goto broken; > + for (j = 0; j < bus->dev_count; j++) { > + if (j == i) > + continue; > + kvm_iodevice_destructor(bus->range[j].dev); > + } > } > > - 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)); > - > -broken: > rcu_assign_pointer(kvm->buses[bus_idx], new_bus); > synchronize_srcu_expedited(&kvm->srcu); > kfree(bus); >
