linux-kernel - [PATCH] maple_tree: Fix mas_prev() and mas

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Message-ID: <20230110181833.1263020-1-Liam.Howlett@oracle.com>
Date:   Tue, 10 Jan 2023 18:18:43 +0000
From:   Liam Howlett <liam.howlett@...cle.com>
To:     "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "maple-tree@...ts.infradead.org" <maple-tree@...ts.infradead.org>
CC:     Liam Howlett <liam.howlett@...cle.com>,
        "syzbot+502859d610c661e56545@...kaller.appspotmail.com" 
        <syzbot+502859d610c661e56545@...kaller.appspotmail.com>
Subject: [PATCH] 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>
---

This should come before 9df3d25a97ec ("mm: expand vma iterator
interface") in the mm-unstable branch.

 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 7d3131ecd5f8..19d272ee4b78 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:
@@ -5917,6 +5917,7 @@ 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;
 	}
 
@@ -6007,6 +6008,9 @@ 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