From: Liam R. Howlett <Liam.Howlett@Oracle.com>
Date: Thu, 24 Nov 2022 15:50:21 +0000 (-0500)
Subject: maple_tree: Protect mas_prev_nentry() from dead nodes
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=f9eacfb30435ba7f177427e03d15faefa0f62ca9;p=users%2Fjedix%2Flinux-maple.git

maple_tree: Protect mas_prev_nentry() from dead nodes

Don't use the pivot array before checking if the node is dead.  This is
for safe use in rcu mode.

Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
---

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index d8504912014e..e66ac3a0e47b 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -4856,6 +4856,11 @@ retry:
 		goto retry;
 	}
 
+	if (offset == mt_pivots[mt])
+		pivot = mas->max;
+	else
+		pivot = pivots[offset];
+
 	while (offset && ((!mas_slot(mas, slots, offset) && pivot >= limit) ||
 	       !pivot))
 		pivot = pivots[--offset];