Liu Bo wrote on 2016/05/02 11:15 -0700:
This adds valid checks for super_total_bytes, super_bytes_used and
super_stripesize.

Reported-by: Vegard Nossum <vegard.nos...@oracle.com>
Reported-by: Quentin Casasnovas <quentin.casasno...@oracle.com>
Signed-off-by: Liu Bo <bo.li....@oracle.com>
---
 fs/btrfs/disk-io.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 4e47849..988d03f 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -4120,6 +4120,20 @@ static int btrfs_check_super_valid(struct btrfs_fs_info 
*fs_info,
         * Hint to catch really bogus numbers, bitflips or so, more exact 
checks are
         * done later
         */
+       if (btrfs_super_total_bytes(sb) == 0) {
+               printk(KERN_ERR "BTRFS: total bytes is zero\n");
+               ret = -EINVAL;
+       }

Would it be better if using "6 * nodesize"?

I'd like to use a precious low limit on total bytes, but we don't have such value, so 6 nodesize would be good.

Thanks,
Qu

+       if (btrfs_super_bytes_used(sb) < 6 * btrfs_super_nodesize(sb)) {
+               printk(KERN_ERR "BTRFS: bytes_used is too small %llu\n",
+                      btrfs_super_bytes_used(sb));
+               ret = -EINVAL;
+       }
+       if (btrfs_super_stripesize(sb) != 4096) {
+               printk(KERN_ERR "BTRFS: invalid stripesize %u\n",
+                      btrfs_super_stripesize(sb));
+               ret = -EINVAL;
+       }
        if (btrfs_super_num_devices(sb) > (1UL << 31))
                printk(KERN_WARNING "BTRFS: suspicious number of devices: 
%llu\n",
                                btrfs_super_num_devices(sb));



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