From: Andrea Parri (Microsoft) <parri.andrea@xxxxxxxxx> Sent: Wednesday, October 6, 2021 6:20 AM
>
> The validation on the length of incoming packets performed in
> storvsc_on_channel_callback() does not apply to unsolicited
> packets with ID of 0 sent by Hyper-V. Adjust the validation
> for such unsolicited packets.
>
> Fixes: 91b1b640b834b2 ("scsi: storvsc: Validate length of incoming packet in storvsc_on_channel_callback()")
> Reported-by: Dexuan Cui <decui@xxxxxxxxxxxxx>
> Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@xxxxxxxxx>
> ---
> Changes since v1[1]:
> - Use sizeof(enum vstor_packet_operation) instead of 48 (Michael Kelley)
> - Filter out FCHBA_DATA packets (Michael Kelley)
>
> Changes since RFC[2]:
> - Merge length checks (Haiyang Zhang)
>
> [1] https://lore.kernel.org/all/20211005114103.3411-1-parri.andrea@xxxxxxxxx/T/#u
> [2] https://lore.kernel.org/all/20210928163732.5908-1-parri.andrea@xxxxxxxxx/T/#u
>
> drivers/scsi/storvsc_drv.c | 34 +++++++++++++++++++++++++---------
> 1 file changed, 25 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
> index ebbbc1299c625..4869ebad7ec97 100644
> --- a/drivers/scsi/storvsc_drv.c
> +++ b/drivers/scsi/storvsc_drv.c
> @@ -1285,11 +1285,15 @@ static void storvsc_on_channel_callback(void *context)
> foreach_vmbus_pkt(desc, channel) {
> struct vstor_packet *packet = hv_pkt_data(desc);
> struct storvsc_cmd_request *request = NULL;
> + u32 pktlen = hv_pkt_datalen(desc);
> u64 rqst_id = desc->trans_id;
> + u32 minlen = rqst_id ? sizeof(struct vstor_packet) -
> + stor_device->vmscsi_size_delta : sizeof(enum vstor_packet_operation);
>
> - if (hv_pkt_datalen(desc) < sizeof(struct vstor_packet) -
> - stor_device->vmscsi_size_delta) {
> - dev_err(&device->device, "Invalid packet len\n");
> + if (pktlen < minlen) {
> + dev_err(&device->device,
> + "Invalid pkt: id=%llu, len=%u, minlen=%u\n",
> + rqst_id, pktlen, minlen);
> continue;
> }
>
> @@ -1302,13 +1306,25 @@ static void storvsc_on_channel_callback(void *context)
> if (rqst_id == 0) {
> /*
> * storvsc_on_receive() looks at the vstor_packet in the message
> - * from the ring buffer. If the operation in the vstor_packet is
> - * COMPLETE_IO, then we call storvsc_on_io_completion(), and
> - * dereference the guest memory address. Make sure we don't call
> - * storvsc_on_io_completion() with a guest memory address that is
> - * zero if Hyper-V were to construct and send such a bogus packet.
> + * from the ring buffer.
> + *
> + * - If the operation in the vstor_packet is COMPLETE_IO, then
> + * we call storvsc_on_io_completion(), and dereference the
> + * guest memory address. Make sure we don't call
> + * storvsc_on_io_completion() with a guest memory address
> + * that is zero if Hyper-V were to construct and send such
> + * a bogus packet.
> + *
> + * - If the operation in the vstor_packet is FCHBA_DATA, then
> + * we call cache_wwn(), and access the data payload area of
> + * the packet (wwn_packet); however, there is no guarantee
> + * that the packet is big enough to contain such area.
> + * Future-proof the code by rejecting such a bogus packet.
The comments look good to me.
> + *
> + * XXX. Filter out all "invalid" operations.
Is this a leftover comment line that should be deleted? I'm not sure about the "XXX".
> */
> - if (packet->operation == VSTOR_OPERATION_COMPLETE_IO) {
> + if (packet->operation == VSTOR_OPERATION_COMPLETE_IO ||
> + packet->operation == VSTOR_OPERATION_FCHBA_DATA) {
> dev_err(&device->device, "Invalid packet with ID of 0\n");
> continue;
> }
> --
> 2.25.1
Other than the seemingly spurious comment line,
Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
