btrfs: fix use after free iterating extrefs
authorChris Mason <clm@fb.com>
Tue, 13 Oct 2015 18:06:48 +0000 (14:06 -0400)
committerChris Mason <clm@fb.com>
Tue, 27 Oct 2015 02:38:28 +0000 (19:38 -0700)
commit2849a854224487bc578b73b64422c3cb3ef93ff5
treececc18105ff992cc0ec13283b28ae6f2c038dd5a
parent849ef9286f30c88113906dc35f44a499c0cb385d
btrfs: fix use after free iterating extrefs

The code for btrfs inode-resolve has never worked properly for
files with enough hard links to trigger extrefs.  It was trying to
get the leaf out of a path after freeing the path:

btrfs_release_path(path);
leaf = path->nodes[0];
item_size = btrfs_item_size_nr(leaf, slot);

The fix here is to use the extent buffer we cloned just a little higher
up to avoid deadlocks caused by using the leaf in the path.

Signed-off-by: Chris Mason <clm@fb.com>
cc: stable@vger.kernel.org # v3.7+
cc: Mark Fasheh <mfasheh@suse.de>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Mark Fasheh <mfasheh@suse.de>
Signed-off-by: Chris Mason <clm@fb.com>
fs/btrfs/backref.c