linux-kernel - [PATCH v4 06/49] maple_tree: Fix mas_prev() and mas

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Date:   Fri, 20 Jan 2023 11:26:07 -0500
From:   "Liam R. Howlett" <Liam.Howlett@...cle.com>
To:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        maple-tree@...ts.infradead.org
Cc:     "Liam R. Howlett" <Liam.Howlett@...cle.com>,
        syzbot+502859d610c661e56545@...kaller.appspotmail.com
Subject: [PATCH v4 06/49] maple_tree: Fix mas_prev() and mas_find() state handling

When mas_prev() does not find anything, set the state to MAS_NONE.

Handle the MAS_NONE in mas_find() like a MAS_START.

Reported-by: syzbot+502859d610c661e56545@...kaller.appspotmail.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
---
 lib/maple_tree.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 14ce355e4149..43bbf1906571 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -4844,7 +4844,7 @@ static inline void *mas_prev_entry(struct ma_state *mas, unsigned long min)
 
 	if (mas->index < min) {
 		mas->index = mas->last = min;
-		mas_pause(mas);
+		mas->node = MAS_NONE;
 		return NULL;
 	}
 retry:
@@ -5918,6 +5918,7 @@ void *mas_prev(struct ma_state *mas, unsigned long min)
 	if (!mas->index) {
 		/* Nothing comes before 0 */
 		mas->last = 0;
+		mas->node = MAS_NONE;
 		return NULL;
 	}
 
@@ -6008,6 +6009,9 @@ void *mas_find(struct ma_state *mas, unsigned long max)
 		mas->index = ++mas->last;
 	}
 
+	if (unlikely(mas_is_none(mas)))
+		mas->node = MAS_START;
+
 	if (unlikely(mas_is_start(mas))) {
 		/* First run or continue */
 		void *entry;
-- 
2.35.1