From: Qu Wenruo <quwenruo.btrfs@gmx.com>
Date: Wed, 23 Aug 2017 07:57:57 +0000 (+0900)
Subject: btrfs: Check if item pointer overlaps with the item itself
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=7f43d4affb2a254d421ab20b0cf65ac2569909fb;p=linux.git

btrfs: Check if item pointer overlaps with the item itself

Function check_leaf() checks if any item pointer points outside of the
leaf, but it doesn't check if the pointer overlaps with the item itself.

Normally only the last item may be the victim, but adding such check is
never a bad idea anyway.

Signed-off-by: Qu Wenruo <quwenruo.btrfs@gmx.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
---

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 6c97ae1e7288e..d1770b3e0385e 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -643,6 +643,13 @@ static noinline int check_leaf(struct btrfs_root *root,
 			return -EUCLEAN;
 		}
 
+		/* Also check if the item pointer overlaps with btrfs item. */
+		if (btrfs_item_nr_offset(slot) + sizeof(struct btrfs_item) >
+		    btrfs_item_ptr_offset(leaf, slot)) {
+			CORRUPT("slot overlap with its data", leaf, root, slot);
+			return -EUCLEAN;
+		}
+
 		prev_key.objectid = key.objectid;
 		prev_key.type = key.type;
 		prev_key.offset = key.offset;