From: Josef Bacik <josef@toxicpanda.com>
Date: Fri, 12 Mar 2021 15:25:26 -0500
Subject: btrfs: tree-checker: check for BTRFS_BLOCK_FLAG_FULL_BACKREF being
 set improperly
Git-commit: 0ebb6bbbd499987248b4ce8f4f7c5eeb6e1fa905
Patch-mainline: v5.13-rc1
References: bsc#1187833

We need to validate that a data extent item does not have the
FULL_BACKREF flag set on its flags.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Acked-by: Nikolay Borisov <nborisov@suse.com>
---
 fs/btrfs/tree-checker.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
index f4ade821307d..a8b2e0d2c025 100644
--- a/fs/btrfs/tree-checker.c
+++ b/fs/btrfs/tree-checker.c
@@ -1290,6 +1290,11 @@ static int check_extent_item(struct extent_buffer *leaf,
 				   key->offset, fs_info->sectorsize);
 			return -EUCLEAN;
 		}
+		if (unlikely(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)) {
+			extent_err(leaf, slot,
+			"invalid extent flag, data has full backref set");
+			return -EUCLEAN;
+		}
 	}
 	ptr = (unsigned long)(struct btrfs_extent_item *)(ei + 1);