[PATCH 3.16.y-ckt 029/254] Btrfs: fix kfree on list_head in btrfs_lookup_csums_range error cleanup

[Luis Henriques]

3.16.7-ckt2 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Chris Mason <clm at fb.com>

commit 6e5aafb27419f32575b27ef9d6a31e5d54661aca upstream.

If we hit any errors in btrfs_lookup_csums_range, we'll loop through all
the csums we allocate and free them.  But the code was using list_entry
incorrectly, and ended up trying to free the on-stack list_head instead.

This bug came from commit 0678b6185

btrfs: Don't BUG_ON kzalloc error in btrfs_lookup_csums_range()

Signed-off-by: Chris Mason <clm at fb.com>
Reported-by: Erik Berg <btrfs at slipsprogrammoer.no>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 fs/btrfs/file-item.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index 54c84daec9b5..74097722ad9f 100644
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -423,7 +423,7 @@ int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end,
 	ret = 0;
 fail:
 	while (ret < 0 && !list_empty(&tmplist)) {
-		sums = list_entry(&tmplist, struct btrfs_ordered_sum, list);
+		sums = list_entry(tmplist.next, struct btrfs_ordered_sum, list);
 		list_del(&sums->list);
 		kfree(sums);
 	}
-- 
2.1.0