[PATCH] bcachefs: Fix NULL dereference in bch2_backpointer_get_node()

[Dan Carpenter]

The bch2_btree_iter_peek_node() function returns both error pointers
and NULL.  Check for NULL before dereferencing "b".

Fixes: 853960d00b4b ("bcachefs: Simplify, fix bch2_backpointer_get_key()")
Signed-off-by: Dan Carpenter <dan.carpen...@linaro.org>
---
 fs/bcachefs/backpointers.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/bcachefs/backpointers.c b/fs/bcachefs/backpointers.c
index ef02c9bb0354..3f9c5c366708 100644
--- a/fs/bcachefs/backpointers.c
+++ b/fs/bcachefs/backpointers.c
@@ -316,7 +316,7 @@ struct btree *bch2_backpointer_get_node(struct btree_trans 
*trans,
        if (IS_ERR(b))
                goto err;
 
-       BUG_ON(b->c.level != bp.level - 1);
+       BUG_ON(b && b->c.level != bp.level - 1);
 
        if (b && extent_matches_bp(c, bp.btree_id, bp.level,
                                   bkey_i_to_s_c(&b->key),
-- 
2.42.0