From 973ce39b8aebfe71d1fcae17ff1dc450699979d5 Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@suse.cz>
Date: Tue, 11 Jun 2019 14:33:38 +0200
Subject: [PATCH] scsi: vmw_pscsi: Fix use-after-free in pvscsi_queue_lck()
References: bsc#1135296
Patch-mainline: v5.2-rc7
Git-commit: 240b4cc8fd5db138b675297d4226ec46594d9b3b

Once we unlock adapter->hw_lock in pvscsi_queue_lck() nothing prevents just
queued scsi_cmnd from completing and freeing the request. Thus cmd->cmnd[0]
dereference can dereference already freed request leading to kernel crashes or
other issues (which one of our customers observed). Store cmd->cmnd[0] in a
local variable before unlocking adapter->hw_lock to fix the issue.

CC: stable@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
---
 drivers/scsi/vmw_pvscsi.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/vmw_pvscsi.c b/drivers/scsi/vmw_pvscsi.c
index ecee4b3ff073..377b07b2feeb 100644
--- a/drivers/scsi/vmw_pvscsi.c
+++ b/drivers/scsi/vmw_pvscsi.c
@@ -763,6 +763,7 @@ static int pvscsi_queue_lck(struct scsi_cmnd *cmd, void (*done)(struct scsi_cmnd
 	struct pvscsi_adapter *adapter = shost_priv(host);
 	struct pvscsi_ctx *ctx;
 	unsigned long flags;
+	unsigned char op;
 
 	spin_lock_irqsave(&adapter->hw_lock, flags);
 
@@ -775,13 +776,14 @@ static int pvscsi_queue_lck(struct scsi_cmnd *cmd, void (*done)(struct scsi_cmnd
 	}
 
 	cmd->scsi_done = done;
+	op = cmd->cmnd[0];
 
 	dev_dbg(&cmd->device->sdev_gendev,
-		"queued cmd %p, ctx %p, op=%x\n", cmd, ctx, cmd->cmnd[0]);
+		"queued cmd %p, ctx %p, op=%x\n", cmd, ctx, op);
 
 	spin_unlock_irqrestore(&adapter->hw_lock, flags);
 
-	pvscsi_kick_io(adapter, cmd->cmnd[0]);
+	pvscsi_kick_io(adapter, op);
 
 	return 0;
 }
-- 
2.16.4