scsi: sd_revalidate_disk prevent NULL ptr deref

Bugzilla: 754518
Upstream-status: Fedora mustard (might be worth dropping...)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index a20da8c25b4f960224fb4d772aafea38c57e1656..fa19e11b46f0d5d40048730d91c2a0117118af57 100644 (file)
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -2717,13 +2717,18 @@ 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.