From: Andrea Parri (Microsoft) <parri.andrea@xxxxxxxxx> Sent: Wednesday, May 4, 2022 5:51 AM
>
> For additional robustness in the face of Hyper-V errors or malicious
> behavior, validate all values that originate from packets that Hyper-V
> has sent to the guest in the host-to-guest ring buffer. Ensure that
> invalid values cannot cause data being copied out of the bounds of the
> source buffer in hv_pci_onchannelcallback().
>
> While at it, remove a redundant validation in hv_pci_generic_compl():
> hv_pci_onchannelcallback() already ensures that all processed incoming
> packets are "at least as large as [in fact larger than] a response".
>
> Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@xxxxxxxxx>
> ---
> drivers/pci/controller/pci-hyperv.c | 27 ++++++++++++++++++++-------
> 1 file changed, 20 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
> index cf2fe5754fde4..9a3e17b682eb7 100644
> --- a/drivers/pci/controller/pci-hyperv.c
> +++ b/drivers/pci/controller/pci-hyperv.c
> @@ -981,11 +981,7 @@ static void hv_pci_generic_compl(void *context, struct
> pci_response *resp,
> {
> struct hv_pci_compl *comp_pkt = context;
>
> - if (resp_packet_size >= offsetofend(struct pci_response, status))
> - comp_pkt->completion_status = resp->status;
> - else
> - comp_pkt->completion_status = -1;
> -
> + comp_pkt->completion_status = resp->status;
> complete(&comp_pkt->host_event);
> }
>
> @@ -1602,8 +1598,13 @@ static void hv_pci_compose_compl(void *context, struct
> pci_response *resp,
> struct pci_create_int_response *int_resp =
> (struct pci_create_int_response *)resp;
>
> + if (resp_packet_size < sizeof(*int_resp)) {
> + comp_pkt->comp_pkt.completion_status = -1;
> + goto out;
> + }
> comp_pkt->comp_pkt.completion_status = resp->status;
> comp_pkt->int_desc = int_resp->int_desc;
> +out:
> complete(&comp_pkt->comp_pkt.host_event);
> }
>
> @@ -2806,7 +2807,8 @@ static void hv_pci_onchannelcallback(void *context)
> case PCI_BUS_RELATIONS:
>
> bus_rel = (struct pci_bus_relations *)buffer;
> - if (bytes_recvd <
> + if (bytes_recvd < sizeof(*bus_rel) ||
> + bytes_recvd <
> struct_size(bus_rel, func,
> bus_rel->device_count)) {
> dev_err(&hbus->hdev->device,
> @@ -2820,7 +2822,8 @@ static void hv_pci_onchannelcallback(void *context)
> case PCI_BUS_RELATIONS2:
>
> bus_rel2 = (struct pci_bus_relations2 *)buffer;
> - if (bytes_recvd <
> + if (bytes_recvd < sizeof(*bus_rel2) ||
> + bytes_recvd <
> struct_size(bus_rel2, func,
> bus_rel2->device_count)) {
> dev_err(&hbus->hdev->device,
> @@ -2834,6 +2837,11 @@ static void hv_pci_onchannelcallback(void *context)
> case PCI_EJECT:
>
> dev_message = (struct pci_dev_incoming *)buffer;
> + if (bytes_recvd < sizeof(*dev_message)) {
> + dev_err(&hbus->hdev->device,
> + "eject message too small\n");
> + break;
> + }
> hpdev = get_pcichild_wslot(hbus,
> dev_message->wslot.slot);
> if (hpdev) {
> @@ -2845,6 +2853,11 @@ static void hv_pci_onchannelcallback(void *context)
> case PCI_INVALIDATE_BLOCK:
>
> inval = (struct pci_dev_inval_block *)buffer;
> + if (bytes_recvd < sizeof(*inval)) {
> + dev_err(&hbus->hdev->device,
> + "invalidate message too small\n");
> + break;
> + }
> hpdev = get_pcichild_wslot(hbus,
> inval->wslot.slot);
> if (hpdev) {
> --
> 2.25.1
I don't see any issues with the code here. But check the function
q_resource_requirements(). Doesn't it need the same treatment as you've
done above with hv_pci_compose_compl()? For completeness, the
fix for q_resource_requirements() should be included in this patch as well.
Michael
