From: Matthew Wilcox (Oracle) <willy@infradead.org>
Date: Sun, 13 Oct 2019 03:21:36 +0000 (-0400)
Subject: maple_tree: Fix mas_dead_node for a trivial tree
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=38daf8125a546671acd3baec61e3892eeb29eaf5;p=users%2Fjedix%2Flinux-maple.git

maple_tree: Fix mas_dead_node for a trivial tree

For a tree with no entries, or an entry only at 0, mas_dead_node()
can be called with a mas->node of NULL.  This node is, by definition,
not dead.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 1d6b370ef4d7..c916a27c0ab9 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -3331,6 +3331,8 @@ static inline int mas_safe_slot(struct ma_state *mas, unsigned char *slot,
 
 static inline int mas_dead_node(struct ma_state *mas, unsigned long index)
 {
+	if (!mas->node)
+		return 0;
 	if (!mt_dead_node(mas->node))
 		return 0;