scsi-sd_revalidate_disk-prevent-NULL-ptr-deref.patch

From 7afe9a8d7dca86a8f35250f21f5f0a62ea2fedf7 Mon Sep 17 00:00:00 2001
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 3d22fc3..07aec76 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -2825,7 +2825,7 @@ static inline u32 logical_to_sectors(struct scsi_device *sdev, u32 blocks)
 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;
 	struct request_queue *q = sdkp->disk->queue;
 	sector_t old_capacity = sdkp->capacity;
 	unsigned char *buffer;
@@ -2833,6 +2833,11 @@ static int sd_revalidate_disk(struct gendisk *disk)
 	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.
-- 
2.5.0