From: "kernel-team@fedoraproject.org" <kernel-team@fedoraproject.org>
Date: Fri, 10 Feb 2012 14:56:13 -0500
Subject: [PATCH] scsi: sd_revalidate_disk prevent NULL ptr deref
 
Bugzilla: 754518
Upstream-status: Fedora mustard (might be worth dropping...)
---
 drivers/scsi/sd.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)
 
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 2c2041ca4b70..e10812d985af 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -2749,13 +2749,18 @@ static int sd_try_extended_inquiry(struct scsi_device *sdp)
 static int sd_revalidate_disk(struct gendisk *disk)
 {
 	struct scsi_disk *sdkp = scsi_disk(disk);
-	struct scsi_device *sdp = sdkp->device;
+	struct scsi_device *sdp;
 	unsigned char *buffer;
 	unsigned int max_xfer;
 
 	SCSI_LOG_HLQUEUE(3, sd_printk(KERN_INFO, sdkp,
 				      "sd_revalidate_disk\n"));
 
+	if (WARN_ONCE((!sdkp), "Invalid scsi_disk from %p\n", disk))
+		goto out;
+
+	sdp = sdkp->device;
+
 	/*
 	 * If the device is offline, don't try and read capacity or any
 	 * of the other niceties.
-- 
2.1.0