+ maple_tree-fix-mas_empty_area-search.patch added to mm-hotfixes-unstable branch

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The patch titled
     Subject: maple_tree: fix mas_empty_area() search
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     maple_tree-fix-mas_empty_area-search.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/maple_tree-fix-mas_empty_area-search.patch

This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: "Liam R. Howlett" <Liam.Howlett@xxxxxxxxxx>
Subject: maple_tree: fix mas_empty_area() search
Date: Fri, 14 Apr 2023 10:57:27 -0400

The internal function of mas_awalk() was incorrectly skipping the last
entry in a node, which could potentially be NULL.  This is only a problem
for the left-most node in the tree - otherwise that NULL would not exist.

Fix mas_awalk() by using the metadata to obtain the end of the node for
the loop and the logical pivot as apposed to the raw pivot value.

Link: https://lkml.kernel.org/r/20230414145728.4067069-2-Liam.Howlett@xxxxxxxxxx
Fixes: 54a611b60590 ("Maple Tree: add new data structure")
Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Reported-by: Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 lib/maple_tree.c |   20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

--- a/lib/maple_tree.c~maple_tree-fix-mas_empty_area-search
+++ a/lib/maple_tree.c
@@ -5056,10 +5056,10 @@ static inline bool mas_anode_descend(str
 {
 	enum maple_type type = mte_node_type(mas->node);
 	unsigned long pivot, min, gap = 0;
-	unsigned char offset;
-	unsigned long *gaps;
-	unsigned long *pivots = ma_pivots(mas_mn(mas), type);
-	void __rcu **slots = ma_slots(mas_mn(mas), type);
+	unsigned char offset, data_end;
+	unsigned long *gaps, *pivots;
+	void __rcu **slots;
+	struct maple_node *node;
 	bool found = false;
 
 	if (ma_is_dense(type)) {
@@ -5067,13 +5067,15 @@ static inline bool mas_anode_descend(str
 		return true;
 	}
 
-	gaps = ma_gaps(mte_to_node(mas->node), type);
+	node = mas_mn(mas);
+	pivots = ma_pivots(node, type);
+	slots = ma_slots(node, type);
+	gaps = ma_gaps(node, type);
 	offset = mas->offset;
 	min = mas_safe_min(mas, pivots, offset);
-	for (; offset < mt_slots[type]; offset++) {
-		pivot = mas_safe_pivot(mas, pivots, offset, type);
-		if (offset && !pivot)
-			break;
+	data_end = ma_data_end(node, type, pivots, mas->max);
+	for (; offset <= data_end; offset++) {
+		pivot = mas_logical_pivot(mas, pivots, offset, type);
 
 		/* Not within lower bounds */
 		if (mas->index > pivot)
_

Patches currently in -mm which might be from Liam.Howlett@xxxxxxxxxx are

mm-mprotect-fix-do_mprotect_pkey-return-on-error.patch
mm-mempolicy-fix-use-after-free-of-vma-iterator.patch
maple_tree-make-maple-state-reusable-after-mas_empty_area_rev.patch
maple_tree-fix-mas_empty_area-search.patch
mm-mmap-regression-fix-for-unmapped_area_topdown.patch




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