[04/14] btrfs: handle invalid extent item reference found in find_first_extent_item()

Commit Message

David Sterba Feb. 8, 2024, 8:59 a.m. UTC

The find_first_extent_item() helper looks up an extent item by a key,
allowing to do an inexact search when key->offset is -1.  It's never
expected to find such item, as it would break the allowed range of a
extent item offset.

Signed-off-by: David Sterba <[e-mail]>
---
 fs/btrfs/scrub.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

Patch

diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index 0123d2728923..c4bd0e60db59 100644
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -1390,8 +1390,15 @@  static int find_first_extent_item(struct btrfs_root *extent_root,
 	ret = btrfs_search_slot(NULL, extent_root, &key, path, 0, 0);
 	if (ret < 0)
 		return ret;
+	if (ret == 0) {
+		/*
+		 * Key with offset -1 found, there would have to exist an extent
+		 * item with such offset, but this is out of the valid range.
+		 */
+		btrfs_release_path(path);
+		return -EUCLEAN;
+	}
 
-	ASSERT(ret > 0);
 	/*
 	 * Here we intentionally pass 0 as @min_objectid, as there could be
 	 * an extent item starting before @search_start.