• Kevin Corry's avatar
    [PATCH] dm stripe: Fix bounds · 8ba32fde
    Kevin Corry authored
    The dm-stripe target currently does not enforce that the size of a stripe
    device be a multiple of the chunk-size.  Under certain conditions, this can
    lead to I/O requests going off the end of an underlying device.  This
    test-case shows one example.
    
    echo "0 100 linear /dev/hdb1 0" | dmsetup create linear0
    echo "0 100 linear /dev/hdb1 100" | dmsetup create linear1
    echo "0 200 striped 2 32 /dev/mapper/linear0 0 /dev/mapper/linear1 0" | \
       dmsetup create stripe0
    dd if=/dev/zero of=/dev/mapper/stripe0 bs=1k
    
    This will produce the output:
    dd: writing '/dev/mapper/stripe0': Input/output error
    97+0 records in
    96+0 records out
    
    And in the kernel log will be:
    attempt to access beyond end of device
    dm-0: rw=0, want=104, limit=100
    
    The patch will check that the table size is a multiple of the stripe
    chunk-size when the table is created, which will prevent the above striped
    device from being created.
    
    This should not affect tools like LVM or EVMS, since in all the cases I can
    think of, striped devices are always created with the sizes being a
    multiple of the chunk-size.
    
    The size of a stripe device must be a multiple of its chunk-size.
    
    (akpm: that typecast is quite gratuitous)
    Signed-off-by: default avatarKevin Corry <kevcorry@us.ibm.com>
    Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
    Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
    8ba32fde
dm-stripe.c 4.92 KB