> -----Original Message-----
> From: Andrea Parri (Microsoft) <parri.andrea@xxxxxxxxx>
> Sent: Tuesday, September 28, 2021 12:38 PM
> To: linux-kernel@xxxxxxxxxxxxxxx; linux-hyperv@xxxxxxxxxxxxxxx; linux-
> scsi@xxxxxxxxxxxxxxx
> Cc: KY Srinivasan <kys@xxxxxxxxxxxxx>; Haiyang Zhang
> <haiyangz@xxxxxxxxxxxxx>; Stephen Hemminger <sthemmin@xxxxxxxxxxxxx>;
> Wei Liu <wei.liu@xxxxxxxxxx>; James E . J . Bottomley
> <jejb@xxxxxxxxxxxxx>; Martin K . Petersen <martin.petersen@xxxxxxxxxx>;
> Michael Kelley <mikelley@xxxxxxxxxxxxx>; Andrea Parri (Microsoft)
> <parri.andrea@xxxxxxxxx>; Dexuan Cui <decui@xxxxxxxxxxxxx>
> Subject: [RFC PATCH] scsi: storvsc: Fix validation for unsolicited
> incoming packets
>
> 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
> by handling such unsolicited packets separately.
>
> 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>
> ---
> The (new) bound, VSTOR_MIN_UNSOL_PKT_SIZE, was "empirically
> derived" based on testing and code auditing. This explains
> the RFC tag...
>
> drivers/scsi/storvsc_drv.c | 17 ++++++++++++++---
> 1 file changed, 14 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
> index ebbbc1299c625..a9bbcbbfb54ee 100644
> --- a/drivers/scsi/storvsc_drv.c
> +++ b/drivers/scsi/storvsc_drv.c
> @@ -292,6 +292,9 @@ struct vmstorage_protocol_version {
> #define STORAGE_CHANNEL_REMOVABLE_FLAG 0x1
> #define STORAGE_CHANNEL_EMULATED_IDE_FLAG 0x2
>
> +/* Lower bound on the size of unsolicited packets with ID of 0 */
> +#define VSTOR_MIN_UNSOL_PKT_SIZE 48
> +
> struct vstor_packet {
> /* Requested operation type */
> enum vstor_packet_operation operation;
> @@ -1285,11 +1288,13 @@ 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;
>
> - if (hv_pkt_datalen(desc) < sizeof(struct vstor_packet) -
> + /* Unsolicited packets with ID of 0 are validated separately
> below */
> + if (rqst_id != 0 && pktlen < sizeof(struct vstor_packet) -
> stor_device->vmscsi_size_delta) {
> - dev_err(&device->device, "Invalid packet len\n");
> + dev_err(&device->device, "Invalid packet: length=%u\n",
> pktlen);
> continue;
> }
>
> @@ -1298,8 +1303,14 @@ static void storvsc_on_channel_callback(void
> *context)
> } else if (rqst_id == VMBUS_RQST_RESET) {
> request = &stor_device->reset_request;
> } else {
> - /* Hyper-V can send an unsolicited message with ID of 0
> */
> if (rqst_id == 0) {
> + if (pktlen < VSTOR_MIN_UNSOL_PKT_SIZE) {
> + dev_err(&device->device,
> + "Invalid packet with ID of 0:
> length=%u\n",
> + pktlen);
> + continue;
> + }
> +
> /*
> * storvsc_on_receive() looks at the vstor_packet
> in the message
> * from the ring buffer. If the operation in the
> vstor_packet is
The patch looks good. But for readability, I'd suggested put the length
checks together like this:
u32 minlen = rqst_id ? sizeof(struct vstor_packet) -
stor_device->vmscsi_size_delta : VSTOR_MIN_UNSOL_PKT_SIZE;
if (pktlen < minlen) {
dev_err(&device->device,
"Invalid pkt: id=%llu, len=%u, minlen=%u\n",
rqst_id, pktlen, minlen);
continue;
}
Thanks.
Signed-off-by: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
