• Andy Isaacson's avatar
    [PATCH] fix read past end of array in md/linear.c · bed31ed9
    Andy Isaacson authored
    When iterating through an array, one must be careful to test one's index
    variable rather than another similarly-named variable.
    
    The loop will read off the end of conf->disks[] in the following
    (pathological) case:
    
      % dd bs=1 seek=840716287 if=/dev/zero of=d1 count=1
      % for i in 2 3 4; do dd if=/dev/zero of=d$i bs=1k count=$(($i+150)); done
      % ./vmlinux ubd0=root ubd1=d1 ubd2=d2 ubd3=d3 ubd4=d4
      # mdadm -C /dev/md0 --level=linear --raid-devices=4 /dev/ubd[1234]
    
    adding some printks, I saw this:
    
      [42949374.960000] hash_spacing = 821120
      [42949374.960000] cnt          = 4
      [42949374.960000] min_spacing  = 801
      [42949374.960000] j=0 size=820928 sz=820928
      [42949374.960000] i=0 sz=820928 hash_spacing=820928
      [42949374.960000] j=1 size=64 sz=64
      [42949374.960000] j=2 size=64 sz=128
      [42949374.960000] j=3 size=64 sz=192
      [42949374.960000] j=4 size=1515870810 sz=1515871002
    
    Cc: Gautham R Shenoy <ego@in.ibm.com>
    Acked-by: default avatarNeil Brown <neilb@cse.unsw.edu.au>
    Cc: <stable@kernel.org>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    bed31ed9
linear.c 11.1 KB