From: Liam R. Howlett <Liam.Howlett@Oracle.com>
Date: Fri, 20 Jan 2023 16:26:04 +0000 (-0500)
Subject: maple_tree: reduce user error potential
X-Git-Tag: v6.3-rc1~113^2~165
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=50e81c82ad947045c7ed26ddc9acb17276b653b6;p=linux-block.git

maple_tree: reduce user error potential

When iterating, a user may operate on the tree and cause the maple state
to be altered and left in an unintuitive state.  Detect this scenario and
correct it by setting to the limit and invalidating the state.

Link: https://lkml.kernel.org/r/20230120162650.984577-4-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 7e3cf5b7e68b..5804c5997598 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -4732,6 +4732,11 @@ static inline void *mas_next_entry(struct ma_state *mas, unsigned long limit)
 	unsigned long last;
 	enum maple_type mt;
 
+	if (mas->index > limit) {
+		mas->index = mas->last = limit;
+		mas_pause(mas);
+		return NULL;
+	}
 	last = mas->last;
 retry:
 	offset = mas->offset;
@@ -4838,6 +4843,11 @@ static inline void *mas_prev_entry(struct ma_state *mas, unsigned long min)
 {
 	void *entry;
 
+	if (mas->index < min) {
+		mas->index = mas->last = min;
+		mas_pause(mas);
+		return NULL;
+	}
 retry:
 	while (likely(!mas_is_none(mas))) {
 		entry = mas_prev_nentry(mas, min, mas->index);