src/patches/suse-2.6.27.31/patches.fixes/block-sanitize-invalid-partition-table-entries

   1 From: Kay Sievers <kay.sievers@vrfy.org>
   2 Date: Thu, 16 Oct 2008 05:04:21 +0000 (-0700)
   3 Subject: block: sanitize invalid partition table entries
   4 Git-commit: ac0d86f5809598ddcd6bfa0ea8245ccc910e9eac
   5 Patch-mainline: 2.6.28
   6 References: bnc#371657
   7
   8 block: sanitize invalid partition table entries
   9
  10 We currently follow blindly what the partition table lies about the
  11 disk, and let the kernel create block devices which can not be accessed.
  12 Trying to identify the device leads to kernel logs full of:
  13   sdb: rw=0, want=73392, limit=28800
  14   attempt to access beyond end of device
  15
  16 Here is an example of a broken partition table, where sda2 starts
  17 behind the end of the disk, and sdb3 is larger than the entire disk:
  18   Disk /dev/sdb: 14 MB, 14745600 bytes
  19   1 heads, 29 sectors/track, 993 cylinders, total 28800 sectors
  20      Device Boot      Start         End      Blocks   Id  System
  21   /dev/sdb1              29        7800        3886   83  Linux
  22   /dev/sdb2           37801       45601        3900+  83  Linux
  23   /dev/sdb3           15602       73402       28900+  83  Linux
  24   /dev/sdb4           23403       28796        2697   83  Linux
  25
  26 The kernel creates these completely invalid devices, which can not be
  27 accessed, or may lead to other unpredictable failures:
  28   grep . /sys/class/block/sdb*/{start,size}
  29   /sys/class/block/sdb/size:28800
  30   /sys/class/block/sdb1/start:29
  31   /sys/class/block/sdb1/size:7772
  32   /sys/class/block/sdb2/start:37801
  33   /sys/class/block/sdb2/size:7801
  34   /sys/class/block/sdb3/start:15602
  35   /sys/class/block/sdb3/size:57801
  36   /sys/class/block/sdb4/start:23403
  37   /sys/class/block/sdb4/size:5394
  38
  39 With this patch, we ignore partitions which start behind the end of the disk,
  40 and limit partitions to the end of the disk if they pretend to be larger:
  41   grep . /sys/class/block/sdb*/{start,size}
  42   /sys/class/block/sdb/size:28800
  43   /sys/class/block/sdb1/start:29
  44   /sys/class/block/sdb1/size:7772
  45   /sys/class/block/sdb3/start:15602
  46   /sys/class/block/sdb3/size:13198
  47   /sys/class/block/sdb4/start:23403
  48   /sys/class/block/sdb4/size:5394
  49
  50 These warnings are printed to the kernel log:
  51   sdb: p2 ignored, start 37801 is behind the end of the disk
  52   sdb: p3 size 57801 limited to end of disk
  53
  54 Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
  55 Cc: Herton Ronaldo Krzesinski <herton@mandriva.com.br>
  56 Cc: Jens Axboe <jens.axboe@oracle.com>
  57 Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
  58 Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
  59 Acked-by: Jeff Mahoney <jeffm@suse.com>
  60 ---
  61
  62  fs/partitions/check.c |   17 +++++++++++++++--
  63  1 file changed, 15 insertions(+), 2 deletions(-)
  64
  65 --- a/fs/partitions/check.c
  66 +++ b/fs/partitions/check.c
  67 @@ -498,10 +498,23 @@ int rescan_partitions(struct gendisk *di
  68                 sector_t from = state->parts[p].from;
  69                 if (!size)
  70                         continue;
  71 +               if (from >= get_capacity(disk)) {
  72 +                       printk(KERN_WARNING
  73 +                              "%s: p%d ignored, start %llu is behind the end of the disk\n",
  74 +                              disk->disk_name, p, (unsigned long long) from);
  75 +                       continue;
  76 +               }
  77                 if (from + size > get_capacity(disk)) {
  78 +                       /*
  79 +                        * we can not ignore partitions of broken tables
  80 +                        * created by for example camera firmware, but we
  81 +                        * limit them to the end of the disk to avoid
  82 +                        * creating invalid block devices
  83 +                        */
  84                         printk(KERN_WARNING
  85 -                               "%s: p%d exceeds device capacity\n",
  86 -                               disk->disk_name, p);
  87 +                              "%s: p%d size %llu limited to end of disk\n",
  88 +                              disk->disk_name, p, (unsigned long long) size);
  89 +                       size = get_capacity(disk) - from;
  90                 }
  91                 res = add_partition(disk, p, from, size, state->parts[p].flags);
  92                 if (res) {