releases/3.8.4/loopdev-remove-an-user-triggerable-oops.patch

   1 From b1a6650406875b9097a032eed89af50682fe1160 Mon Sep 17 00:00:00 2001
   2 From: Guo Chao <yan@linux.vnet.ibm.com>
   3 Date: Thu, 21 Feb 2013 15:16:49 -0800
   4 Subject: loopdev: remove an user triggerable oops
   5
   6 From: Guo Chao <yan@linux.vnet.ibm.com>
   7
   8 commit b1a6650406875b9097a032eed89af50682fe1160 upstream.
   9
  10 When loopdev is built as module and we pass an invalid parameter,
  11 loop_init() will return directly without deregister misc device, which
  12 will cause an oops when insert loop module next time because we left some
  13 garbage in the misc device list.
  14
  15 Test case:
  16 sudo modprobe loop max_part=1024
  17 (failed due to invalid parameter)
  18 sudo modprobe loop
  19 (oops)
  20
  21 Clean up nicely to avoid such oops.
  22
  23 Signed-off-by: Guo Chao <yan@linux.vnet.ibm.com>
  24 Cc: Alexander Viro <viro@zeniv.linux.org.uk>
  25 Cc: Guo Chao <yan@linux.vnet.ibm.com>
  26 Cc: M. Hindess <hindessm@uk.ibm.com>
  27 Cc: Nikanth Karthikesan <knikanth@suse.de>
  28 Cc: Jens Axboe <axboe@kernel.dk>
  29 Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
  30 Signed-off-by: Jens Axboe <axboe@kernel.dk>
  31 Acked-by: Jeff Mahoney <jeffm@suse.com>
  32 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  33
  34 ---
  35  drivers/block/loop.c |   22 ++++++++++++++++------
  36  1 file changed, 16 insertions(+), 6 deletions(-)
  37
  38 --- a/drivers/block/loop.c
  39 +++ b/drivers/block/loop.c
  40 @@ -1856,11 +1856,15 @@ static int __init loop_init(void)
  41                 max_part = (1UL << part_shift) - 1;
  42         }
  43
  44 -       if ((1UL << part_shift) > DISK_MAX_PARTS)
  45 -               return -EINVAL;
  46 +       if ((1UL << part_shift) > DISK_MAX_PARTS) {
  47 +               err = -EINVAL;
  48 +               goto misc_out;
  49 +       }
  50
  51 -       if (max_loop > 1UL << (MINORBITS - part_shift))
  52 -               return -EINVAL;
  53 +       if (max_loop > 1UL << (MINORBITS - part_shift)) {
  54 +               err = -EINVAL;
  55 +               goto misc_out;
  56 +       }
  57
  58         /*
  59          * If max_loop is specified, create that many devices upfront.
  60 @@ -1878,8 +1882,10 @@ static int __init loop_init(void)
  61                 range = 1UL << MINORBITS;
  62         }
  63
  64 -       if (register_blkdev(LOOP_MAJOR, "loop"))
  65 -               return -EIO;
  66 +       if (register_blkdev(LOOP_MAJOR, "loop")) {
  67 +               err = -EIO;
  68 +               goto misc_out;
  69 +       }
  70
  71         blk_register_region(MKDEV(LOOP_MAJOR, 0), range,
  72                                   THIS_MODULE, loop_probe, NULL, NULL);
  73 @@ -1892,6 +1898,10 @@ static int __init loop_init(void)
  74
  75         printk(KERN_INFO "loop: module loaded\n");
  76         return 0;
  77 +
  78 +misc_out:
  79 +       misc_deregister(&loop_misc);
  80 +       return err;
  81  }
  82
  83  static int loop_exit_cb(int id, void *ptr, void *data)