This is a note to let you know that I've just added the patch titled
maple_tree: be more cautious about dead nodes
to the 6.2-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
maple_tree-be-more-cautious-about-dead-nodes.patch
and it can be found in the queue-6.2 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From stable-owner@xxxxxxxxxxxxxxx Tue Apr 11 17:13:00 2023
From: "Liam R. Howlett" <Liam.Howlett@xxxxxxxxxx>
Date: Tue, 11 Apr 2023 11:10:48 -0400
Subject: maple_tree: be more cautious about dead nodes
To: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>, stable@xxxxxxxxxxxxxxx
Cc: maple-tree@xxxxxxxxxxxxxxxxxxx, linux-mm@xxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, "Liam R. Howlett" <Liam.Howlett@xxxxxxxxxx>, Stable@xxxxxxxxxxxxxxx, Liam Howlett <Liam.Howlett@xxxxxxxxxx>
Message-ID: <20230411151055.2910579-8-Liam.Howlett@xxxxxxxxxx>
From: "Liam R. Howlett" <Liam.Howlett@xxxxxxxxxx>
commit 39d0bd86c499ecd6abae42a9b7112056c5560691 upstream.
ma_pivots() and ma_data_end() may be called with a dead node. Ensure to
that the node isn't dead before using the returned values.
This is necessary for RCU mode of the maple tree.
Link: https://lkml.kernel.org/r/20230227173632.3292573-1-surenb@xxxxxxxxxx
Link: https://lkml.kernel.org/r/20230227173632.3292573-2-surenb@xxxxxxxxxx
Fixes: 54a611b60590 ("Maple Tree: add new data structure")
Cc: <Stable@xxxxxxxxxxxxxxx>
Signed-off-by: Liam Howlett <Liam.Howlett@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
lib/maple_tree.c | 52 +++++++++++++++++++++++++++++++++++++++++++---------
1 file changed, 43 insertions(+), 9 deletions(-)
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -539,6 +539,7 @@ static inline bool ma_dead_node(const st
return (parent == node);
}
+
/*
* mte_dead_node() - check if the @enode is dead.
* @enode: The encoded maple node
@@ -620,6 +621,8 @@ static inline unsigned int mas_alloc_req
* @node - the maple node
* @type - the node type
*
+ * In the event of a dead node, this array may be %NULL
+ *
* Return: A pointer to the maple node pivots
*/
static inline unsigned long *ma_pivots(struct maple_node *node,
@@ -1091,8 +1094,11 @@ static int mas_ascend(struct ma_state *m
a_type = mas_parent_enum(mas, p_enode);
a_node = mte_parent(p_enode);
a_slot = mte_parent_slot(p_enode);
- pivots = ma_pivots(a_node, a_type);
a_enode = mt_mk_node(a_node, a_type);
+ pivots = ma_pivots(a_node, a_type);
+
+ if (unlikely(ma_dead_node(a_node)))
+ return 1;
if (!set_min && a_slot) {
set_min = true;
@@ -1398,6 +1404,9 @@ static inline unsigned char ma_data_end(
{
unsigned char offset;
+ if (!pivots)
+ return 0;
+
if (type == maple_arange_64)
return ma_meta_end(node, type);
@@ -1433,6 +1442,9 @@ static inline unsigned char mas_data_end
return ma_meta_end(node, type);
pivots = ma_pivots(node, type);
+ if (unlikely(ma_dead_node(node)))
+ return 0;
+
offset = mt_pivots[type] - 1;
if (likely(!pivots[offset]))
return ma_meta_end(node, type);
@@ -4498,6 +4510,9 @@ static inline int mas_prev_node(struct m
node = mas_mn(mas);
slots = ma_slots(node, mt);
pivots = ma_pivots(node, mt);
+ if (unlikely(ma_dead_node(node)))
+ return 1;
+
mas->max = pivots[offset];
if (offset)
mas->min = pivots[offset - 1] + 1;
@@ -4519,6 +4534,9 @@ static inline int mas_prev_node(struct m
slots = ma_slots(node, mt);
pivots = ma_pivots(node, mt);
offset = ma_data_end(node, mt, pivots, mas->max);
+ if (unlikely(ma_dead_node(node)))
+ return 1;
+
if (offset)
mas->min = pivots[offset - 1] + 1;
@@ -4567,6 +4585,7 @@ static inline int mas_next_node(struct m
struct maple_enode *enode;
int level = 0;
unsigned char offset;
+ unsigned char node_end;
enum maple_type mt;
void __rcu **slots;
@@ -4590,7 +4609,11 @@ static inline int mas_next_node(struct m
node = mas_mn(mas);
mt = mte_node_type(mas->node);
pivots = ma_pivots(node, mt);
- } while (unlikely(offset == ma_data_end(node, mt, pivots, mas->max)));
+ node_end = ma_data_end(node, mt, pivots, mas->max);
+ if (unlikely(ma_dead_node(node)))
+ return 1;
+
+ } while (unlikely(offset == node_end));
slots = ma_slots(node, mt);
pivot = mas_safe_pivot(mas, pivots, ++offset, mt);
@@ -4606,6 +4629,9 @@ static inline int mas_next_node(struct m
mt = mte_node_type(mas->node);
slots = ma_slots(node, mt);
pivots = ma_pivots(node, mt);
+ if (unlikely(ma_dead_node(node)))
+ return 1;
+
offset = 0;
pivot = pivots[0];
}
@@ -4652,11 +4678,14 @@ static inline void *mas_next_nentry(stru
return NULL;
}
- pivots = ma_pivots(node, type);
slots = ma_slots(node, type);
- mas->index = mas_safe_min(mas, pivots, mas->offset);
+ pivots = ma_pivots(node, type);
count = ma_data_end(node, type, pivots, mas->max);
- if (ma_dead_node(node))
+ if (unlikely(ma_dead_node(node)))
+ return NULL;
+
+ mas->index = mas_safe_min(mas, pivots, mas->offset);
+ if (unlikely(ma_dead_node(node)))
return NULL;
if (mas->index > max)
@@ -4814,6 +4843,11 @@ retry:
slots = ma_slots(mn, mt);
pivots = ma_pivots(mn, mt);
+ if (unlikely(ma_dead_node(mn))) {
+ mas_rewalk(mas, index);
+ goto retry;
+ }
+
if (offset == mt_pivots[mt])
pivot = mas->max;
else
@@ -6616,11 +6650,11 @@ static inline void *mas_first_entry(stru
while (likely(!ma_is_leaf(mt))) {
MT_BUG_ON(mas->tree, mte_dead_node(mas->node));
slots = ma_slots(mn, mt);
- pivots = ma_pivots(mn, mt);
- max = pivots[0];
entry = mas_slot(mas, slots, 0);
+ pivots = ma_pivots(mn, mt);
if (unlikely(ma_dead_node(mn)))
return NULL;
+ max = pivots[0];
mas->node = entry;
mn = mas_mn(mas);
mt = mte_node_type(mas->node);
@@ -6640,13 +6674,13 @@ static inline void *mas_first_entry(stru
if (likely(entry))
return entry;
- pivots = ma_pivots(mn, mt);
- mas->index = pivots[0] + 1;
mas->offset = 1;
entry = mas_slot(mas, slots, 1);
+ pivots = ma_pivots(mn, mt);
if (unlikely(ma_dead_node(mn)))
return NULL;
+ mas->index = pivots[0] + 1;
if (mas->index > limit)
goto none;
Patches currently in stable-queue which might be from stable-owner@xxxxxxxxxxxxxxx are
queue-6.2/maple_tree-fix-potential-rcu-issue.patch
queue-6.2/maple_tree-add-smp_rmb-to-dead-node-detection.patch
queue-6.2/maple_tree-add-rcu-lock-checking-to-rcu-callback-functions.patch
queue-6.2/maple_tree-fix-handle-of-invalidated-state-in-mas_wr_store_setup.patch
queue-6.2/maple_tree-reduce-user-error-potential.patch
queue-6.2/maple_tree-fix-mas_prev-and-mas_find-state-handling.patch
queue-6.2/maple_tree-remove-gfp_zero-from-kmem_cache_alloc-and-kmem_cache_alloc_bulk.patch
queue-6.2/maple_tree-be-more-cautious-about-dead-nodes.patch
queue-6.2/mm-enable-maple-tree-rcu-mode-by-default.patch
queue-6.2/maple_tree-detect-dead-nodes-in-mas_start.patch
queue-6.2/maple_tree-fix-freeing-of-nodes-in-rcu-mode.patch
queue-6.2/maple_tree-remove-extra-smp_wmb-from-mas_dead_leaves.patch
queue-6.2/maple_tree-refine-ma_state-init-from-mas_start.patch
