| From: Johannes Thumshirn <jthumshirn@suse.de> |
| Date: Mon, 18 Feb 2019 11:28:37 +0100 |
| Subject: btrfs: ensure that a DUP or RAID1 block group has exactly two stripes |
| |
| commit 349ae63f40638a28c6fce52e8447c2d14b84cc0c upstream. |
| |
| We recently had a customer issue with a corrupted filesystem. When |
| trying to mount this image btrfs panicked with a division by zero in |
| calc_stripe_length(). |
| |
| The corrupt chunk had a 'num_stripes' value of 1. calc_stripe_length() |
| takes this value and divides it by the number of copies the RAID profile |
| is expected to have to calculate the amount of data stripes. As a DUP |
| profile is expected to have 2 copies this division resulted in 1/2 = 0. |
| Later then the 'data_stripes' variable is used as a divisor in the |
| stripe length calculation which results in a division by 0 and thus a |
| kernel panic. |
| |
| When encountering a filesystem with a DUP block group and a |
| 'num_stripes' value unequal to 2, refuse mounting as the image is |
| corrupted and will lead to unexpected behaviour. |
| |
| Code inspection showed a RAID1 block group has the same issues. |
| |
| Fixes: e06cd3dd7cea ("Btrfs: add validadtion checks for chunk loading") |
| Reviewed-by: Qu Wenruo <wqu@suse.com> |
| Reviewed-by: Nikolay Borisov <nborisov@suse.com> |
| Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de> |
| Reviewed-by: David Sterba <dsterba@suse.com> |
| Signed-off-by: David Sterba <dsterba@suse.com> |
| Signed-off-by: Ben Hutchings <ben@decadent.org.uk> |
| --- |
| fs/btrfs/volumes.c | 4 ++-- |
| 1 file changed, 2 insertions(+), 2 deletions(-) |
| |
| --- a/fs/btrfs/volumes.c |
| +++ b/fs/btrfs/volumes.c |
| @@ -5884,10 +5884,10 @@ static int btrfs_check_chunk_valid(struc |
| } |
| |
| if ((type & BTRFS_BLOCK_GROUP_RAID10 && sub_stripes != 2) || |
| - (type & BTRFS_BLOCK_GROUP_RAID1 && num_stripes < 1) || |
| + (type & BTRFS_BLOCK_GROUP_RAID1 && num_stripes != 2) || |
| (type & BTRFS_BLOCK_GROUP_RAID5 && num_stripes < 2) || |
| (type & BTRFS_BLOCK_GROUP_RAID6 && num_stripes < 3) || |
| - (type & BTRFS_BLOCK_GROUP_DUP && num_stripes > 2) || |
| + (type & BTRFS_BLOCK_GROUP_DUP && num_stripes != 2) || |
| ((type & BTRFS_BLOCK_GROUP_PROFILE_MASK) == 0 && |
| num_stripes != 1)) { |
| btrfs_err(root->fs_info, |
