btrfs: promote debugging asserts to full-fledged checks in validate_super

Syzbot managed to trigger this assert while performing its fuzzing.
Turns out it's better to have those asserts turned into full-fledged
checks so that in case buggy btrfs images are mounted the users gets
an error and mounting is stopped. Alternatively with CONFIG_BTRFS_ASSERT
disabled such image would have been erroneously allowed to be mounted.

Reported-by: syzbot+a6bf271c02e4fe66b4e4@syzkaller.appspotmail.com
CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ add uuids to the messages ]
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index c9a3036..8d386a5 100644 (file)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2648,6 +2648,24 @@ static int validate_super(struct btrfs_fs_info *fs_info,
                ret = -EINVAL;
        }
 
+       if (memcmp(fs_info->fs_devices->fsid, fs_info->super_copy->fsid,
+                  BTRFS_FSID_SIZE)) {
+               btrfs_err(fs_info,
+               "superblock fsid doesn't match fsid of fs_devices: %pU != %pU",
+                       fs_info->super_copy->fsid, fs_info->fs_devices->fsid);
+               ret = -EINVAL;
+       }
+
+       if (btrfs_fs_incompat(fs_info, METADATA_UUID) &&
+           memcmp(fs_info->fs_devices->metadata_uuid,
+                  fs_info->super_copy->metadata_uuid, BTRFS_FSID_SIZE)) {
+               btrfs_err(fs_info,
+"superblock metadata_uuid doesn't match metadata uuid of fs_devices: %pU != %pU",
+                       fs_info->super_copy->metadata_uuid,
+                       fs_info->fs_devices->metadata_uuid);
+               ret = -EINVAL;
+       }
+
        if (memcmp(fs_info->fs_devices->metadata_uuid, sb->dev_item.fsid,
                   BTRFS_FSID_SIZE) != 0) {
                btrfs_err(fs_info,
@@ -3279,14 +3297,6 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
 
        disk_super = fs_info->super_copy;
 
-       ASSERT(!memcmp(fs_info->fs_devices->fsid, fs_info->super_copy->fsid,
-                      BTRFS_FSID_SIZE));
-
-       if (btrfs_fs_incompat(fs_info, METADATA_UUID)) {
-               ASSERT(!memcmp(fs_info->fs_devices->metadata_uuid,
-                               fs_info->super_copy->metadata_uuid,
-                               BTRFS_FSID_SIZE));
-       }
 
        features = btrfs_super_flags(disk_super);
        if (features & BTRFS_SUPER_FLAG_CHANGING_FSID_V2) {