linux-kernel - [PATCH] maple_tree: Fix mas_next() when already on the last node entry

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Date:   Tue, 17 May 2022 14:59:22 +0000
From:   Liam Howlett <liam.howlett@...cle.com>
To:     "maple-tree@...ts.infradead.org" <maple-tree@...ts.infradead.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH] maple_tree: Fix mas_next() when already on the last node
 entry

It is possible to return the metadata as the next entry if the last node
entry is already in the maple state and the limit is not reached.  Check
for this condition in mas_next_nentry() where the node end is returned.

Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
---
 lib/maple_tree.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 967631055210..751aafd01c42 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -4547,6 +4547,9 @@ static inline void *mas_next_nentry(struct ma_state *mas,
 		return NULL;
 
 	count = ma_data_end(node, type, pivots, mas->max);
+	if (mas->offset > count)
+		return NULL;
+
 	while (mas->offset < count) {
 		pivot = pivots[mas->offset];
 		entry = mas_slot(mas, slots, mas->offset);
-- 
2.35.1