Rustam Kovhaev <[email protected]> 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: [email protected]
> Link: https://syzkaller.appspot.com/bug?extid=f196caa45793d6374707
> Signed-off-by: Rustam Kovhaev <[email protected]>
> ---
> 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 <[email protected]>
--
Vitaly
