From: Finn Thain <fthain@telegraphics.com.au>
Date: Thu, 27 Sep 2018 11:17:11 +1000
Subject: scsi: NCR5380: Check for invalid reselection target
Git-commit: 7ef55f6744c45e3d7c85a3f74ada39b67ac741dd
Patch-mainline: v4.20-rc1
References: git-fixes

The X3T9.2 specification (draft) says, under "6.1.4.1 RESELECTION", that "the
initiator shall not respond to a RESELECTION phase if other than two SCSI ID
bits are on the DATA BUS." This issue (too many bits set) has been observed in
the wild, so add a check.

Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Lee Duncan <lduncan@suse.com>
---
 drivers/scsi/NCR5380.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/scsi/NCR5380.c b/drivers/scsi/NCR5380.c
index e96a48b9e86c..3058b68b6740 100644
--- a/drivers/scsi/NCR5380.c
+++ b/drivers/scsi/NCR5380.c
@@ -2016,6 +2016,11 @@ static void NCR5380_reselect(struct Scsi_Host *instance)
 	NCR5380_write(MODE_REG, MR_BASE);
 
 	target_mask = NCR5380_read(CURRENT_SCSI_DATA_REG) & ~(hostdata->id_mask);
+	if (!target_mask || target_mask & (target_mask - 1)) {
+		shost_printk(KERN_WARNING, instance,
+			     "reselect: bad target_mask 0x%02x\n", target_mask);
+		return;
+	}
 
 	dsprintk(NDEBUG_RESELECTION, instance, "reselect\n");