scsi: NCR5380: Initialize buffer for MSG IN and STATUS transfers

Following an incomplete transfer in MSG IN phase, the driver would not
notice the problem and would make use of invalid data. Initialize 'tmp'
appropriately and bail out if no message was received. For STATUS phase,
preserve the existing status code unless a new value was transferred.

Tested-by: Stan Johnson <[email protected]>
Signed-off-by: Finn Thain <[email protected]>
Link: https://lore.kernel.org/r/52e02a8812ae1a2d810d7f9f7fd800c3ccc320c4.1723001788.git.fthain@linux-m68k.org
Signed-off-by: Martin K. Petersen <[email protected]>

Author: fthain

drivers/scsi/NCR5380.c

@@ -1807,8 +1807,11 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
 				return;
 			case PHASE_MSGIN:
 				len = 1;
+				tmp = 0xff;
 				data = &tmp;
 				NCR5380_transfer_pio(instance, &phase, &len, &data, 0);
+				if (tmp == 0xff)
+					break;
 				ncmd->message = tmp;
 
 				switch (tmp) {
@@ -1996,6 +1999,7 @@ static void NCR5380_information_transfer(struct Scsi_Host *instance)
 				break;
 			case PHASE_STATIN:
 				len = 1;
+				tmp = ncmd->status;
 				data = &tmp;
 				NCR5380_transfer_pio(instance, &phase, &len, &data, 0);
 				ncmd->status = tmp;