btrfs: Check if item pointer overlaps with the item itself

commit 7f43d4affb2a254d421ab20b0cf65ac2569909fb upstream.

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>
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index d513650d1b77326ea717c8c90f9a14cea0b85748..d2725a8798febbaeb766ba5e75cdba50bc936053 100644 (file)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -621,6 +621,13 @@ 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;