bcachefs: Fix a null ptr deref in bch2_get_alloc_in_memory_pos()

Reported-by: smatch
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

diff --git a/fs/bcachefs/backpointers.c b/fs/bcachefs/backpointers.c
index 43defea..cc85615 100644 (file)
--- a/fs/bcachefs/backpointers.c
+++ b/fs/bcachefs/backpointers.c
@@ -703,7 +703,7 @@ static int bch2_get_alloc_in_memory_pos(struct btree_trans *trans,
 
                --btree_nodes;
                if (!btree_nodes) {
-                       *end = alloc_k.k->p;
+                       *end = alloc_k.k ? alloc_k.k->p : SPOS_MAX;
                        break;
                }