block: Fix NULL pointer dereference in sd_revalidate_disk

Since 2.6.39 (1196f8b), when a driver returns -ENOMEDIUM for open(),
__blkdev_get() calls rescan_partitions() to remove
in-kernel partition structures and raise KOBJ_CHANGE uevent.

However it ends up calling driver's revalidate_disk without open
and could cause oops.

In the case of SCSI:

  process A                  process B
  ----------------------------------------------
  sys_open
    __blkdev_get
      sd_open
        returns -ENOMEDIUM
                             scsi_remove_device
                               <scsi_device torn down>
      rescan_partitions
        sd_revalidate_disk
          <oops>
Oopses are reported here:
http://marc.info/?l=linux-scsi&m=132388619710052

This patch separates the partition invalidation from rescan_partitions()
and use it for -ENOMEDIUM case.

Reported-by: Huajun Li <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Acked-by: Tejun Heo <[email protected]>
Cc: [email protected]
Signed-off-by: Jens Axboe <[email protected]>

0 files changed, 0 insertions, 0 deletions