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 for such unsolicited packets.

Link: https://lore.kernel.org/r/20211007122828.469289-1-parri.andrea@gmail.com
Fixes: 91b1b640b834b2 ("scsi: storvsc: Validate length of incoming packet in storvsc_on_channel_callback()")
Reported-by: Dexuan Cui <decui@microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
index ebbbc12..9eb1b88 100644 (file)
--- 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 +1306,23 @@ 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.
                                 */
-                               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;
                                }