SCSI: sd: revive sd_index_lock

commit 4034cc68157bfa0b6622efe368488d3d3e20f4e6 upstream.

Commit f27bac2761cab5a2e212dea602d22457a9aa6943 which converted sd to
use ida instead of idr incorrectly removed sd_index_lock around id
allocation and free.  idr/ida do have internal locks but they protect
their free object lists not the allocation itself.  The caller is
responsible for that.  This missing synchronization led to the same id
being assigned to multiple devices leading to oops.

Reported and tracked down by Stuart Hayes of Dell.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 5081b3981d3c241487a9bf4f29be69796eb8e7cb..726d1476aa8ded70a7b00c70961ad016f8d7e076 100644 (file)
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -106,6 +106,7 @@ static void scsi_disk_release(struct device *cdev);
 static void sd_print_sense_hdr(struct scsi_disk *, struct scsi_sense_hdr *);
 static void sd_print_result(struct scsi_disk *, int);
 
+static DEFINE_SPINLOCK(sd_index_lock);
 static DEFINE_IDA(sd_index_ida);
 
 /* This semaphore is used to mediate the 0->1 reference get in the
@@ -1847,7 +1848,9 @@ static int sd_probe(struct device *dev)
                if (!ida_pre_get(&sd_index_ida, GFP_KERNEL))
                        goto out_put;
 
+               spin_lock(&sd_index_lock);
                error = ida_get_new(&sd_index_ida, &index);
+               spin_unlock(&sd_index_lock);
        } while (error == -EAGAIN);
 
        if (error)
@@ -1910,7 +1913,9 @@ static int sd_probe(struct device *dev)
        return 0;
 
  out_free_index:
+       spin_lock(&sd_index_lock);
        ida_remove(&sd_index_ida, index);
+       spin_unlock(&sd_index_lock);
  out_put:
        put_disk(gd);
  out_free:
@@ -1960,7 +1965,9 @@ static void scsi_disk_release(struct device *dev)
        struct scsi_disk *sdkp = to_scsi_disk(dev);
        struct gendisk *disk = sdkp->disk;
        
+       spin_lock(&sd_index_lock);
        ida_remove(&sd_index_ida, sdkp->index);
+       spin_unlock(&sd_index_lock);
 
        disk->private_data = NULL;
        put_disk(disk);