linux-kernel - [PATCH AUTOSEL 4.9 57/66] scsi: NCR5380: Check for invalid reselection target

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Date:   Sat,  9 Nov 2019 21:48:36 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Finn Thain <fthain@...egraphics.com.au>,
        Michael Schmitz <schmitzmic@...il.com>,
        "Martin K . Petersen" <martin.petersen@...cle.com>,
        Sasha Levin <sashal@...nel.org>, linux-scsi@...r.kernel.org
Subject: [PATCH AUTOSEL 4.9 57/66] scsi: NCR5380: Check for invalid reselection target

From: Finn Thain <fthain@...egraphics.com.au>

[ Upstream commit 7ef55f6744c45e3d7c85a3f74ada39b67ac741dd ]

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@...il.com>
Signed-off-by: Finn Thain <fthain@...egraphics.com.au>
Signed-off-by: Martin K. Petersen <martin.petersen@...cle.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/scsi/NCR5380.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/scsi/NCR5380.c b/drivers/scsi/NCR5380.c
index 35419ba32c467..15c0fff7519be 100644
--- a/drivers/scsi/NCR5380.c
+++ b/drivers/scsi/NCR5380.c
@@ -2102,6 +2102,11 @@ 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");
 
-- 
2.20.1