On Wed, Sep 02, 2020 at 06:34:11PM -0500, Gustavo A. R. Silva wrote: > 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); > > hi Gustavo, thank you for the review, i'll send the new patch. Vitaly, i think i will need to drop your "Reviewed-by", because there is going to be a bit more changes
