• Alasdair G Kergon's avatar
    [PATCH] dm: fix find_device race · bfc5ecdf
    Alasdair G Kergon authored
    There is a race between dev_create() and find_device().
    
    If the mdptr has not yet been stored against a device, find_device() needs to
    behave as though no device was found.  It already returns NULL, but there is a
    dm_put() missing: it must drop the reference dm_get_md() took.
    
    The bug was introduced by dm-fix-mapped-device-ref-counting.patch.
    
    It manifests itself if another dm ioctl attempts to reference a newly-created
    device while the device creation ioctl is still running.  The consequence is
    that the device cannot be removed until the machine is rebooted.  Certain udev
    configurations can lead to this happening.
    Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
    Cc: <dm-devel@redhat.com>
    Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
    bfc5ecdf
dm-ioctl.c 30.2 KB