Btrfs: add NULL check for do_walk_down()

btrfs_find_create_tree_block() may return NULL, so we must check the returned
value, or we will access a NULL pointer.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 1727b26fb194..503a18eaef52 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -5205,6 +5205,8 @@ static noinline int do_walk_down(struct btrfs_trans_handle *trans,
         next = btrfs_find_tree_block(root, bytenr, blocksize);
         if (!next) {
                 next = btrfs_find_create_tree_block(root, bytenr, blocksize);
+                if (!next)
+                        return -ENOMEM;
                 reada = 1;
         }
         btrfs_tree_lock(next);
@@ -5417,7 +5419,8 @@ static noinline int walk_down_tree(struct btrfs_trans_handle *trans,
                 if (ret > 0) {
                         path->slots[level]++;
                         continue;
-                }
+                } else if (ret < 0)
+                        return ret;
                 level = wc->level;
         }
         return 0;