From: David Sterba <dsterba@suse.com>
Date: Wed, 24 Jan 2024 21:41:01 +0000 (+0100)
Subject: btrfs: handle invalid extent item reference found in extent_from_logical()
X-Git-Tag: v6.9-rc1~172^2~51
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=11dcc86ebac88ca878e661eab4ce2a5a6c611edd;p=thirdparty%2Flinux.git

btrfs: handle invalid extent item reference found in extent_from_logical()

The extent_from_logical() 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.

The same error is already handled in btrfs_backref_iter_start() so add a
comment for consistency.

Signed-off-by: David Sterba <dsterba@suse.com>
---

diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index 0fa27ed802f6f..6ba743ddfe211 100644
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -2227,6 +2227,13 @@ int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
 	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.
+		 */
+		return -EUCLEAN;
+	}
 
 	ret = btrfs_previous_extent_item(extent_root, path, 0);
 	if (ret) {
@@ -2870,6 +2877,10 @@ int btrfs_backref_iter_start(struct btrfs_backref_iter *iter, u64 bytenr)
 	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.
+		 */
 		ret = -EUCLEAN;
 		goto release;
 	}