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maple_tree: be more cautious about dead nodes

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commit 39d0bd86c4 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@google.com
Link: https://lkml.kernel.org/r/20230227173632.3292573-2-surenb@google.com
Fixes: 54a611b605 ("Maple Tree: add new data structure")
Cc: <Stable@vger.kernel.org>
Signed-off-by: Liam Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Liam R. Howlett 2023-04-11 11:10:48 -04:00 committed by Greg Kroah-Hartman
parent 0a0372d1d2
commit 64cb480523
1 changed files with 43 additions and 9 deletions
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52
lib/maple_tree.c
View file

@ -534,6 +534,7 @@ static inline bool ma_dead_node(const struct maple_node *node)
return (parent == node);
}
/*
* mte_dead_node() - check if the @enode is dead.
* @enode: The encoded maple node
@ -615,6 +616,8 @@ static inline unsigned int mas_alloc_req(const struct ma_state *mas)
* @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,
@ -1086,8 +1089,11 @@ static int mas_ascend(struct ma_state *mas)
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;
@ -1393,6 +1399,9 @@ static inline unsigned char ma_data_end(struct maple_node *node,
{
unsigned char offset;
if (!pivots)
return 0;
if (type == maple_arange_64)
return ma_meta_end(node, type);
@ -1428,6 +1437,9 @@ static inline unsigned char mas_data_end(struct ma_state *mas)
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);
@ -4493,6 +4505,9 @@ static inline int mas_prev_node(struct ma_state *mas, unsigned long min)
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;
@ -4514,6 +4529,9 @@ static inline int mas_prev_node(struct ma_state *mas, unsigned long min)
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;
@ -4562,6 +4580,7 @@ static inline int mas_next_node(struct ma_state *mas, struct maple_node *node,
struct maple_enode *enode;
int level = 0;
unsigned char offset;
unsigned char node_end;
enum maple_type mt;
void __rcu **slots;
@ -4585,7 +4604,11 @@ static inline int mas_next_node(struct ma_state *mas, struct maple_node *node,
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);
@ -4601,6 +4624,9 @@ static inline int mas_next_node(struct ma_state *mas, struct maple_node *node,
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];
}
@ -4647,11 +4673,14 @@ static inline void *mas_next_nentry(struct ma_state *mas,
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)
@ -4809,6 +4838,11 @@ static inline void *mas_prev_nentry(struct ma_state *mas, unsigned long limit,
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
@ -6611,11 +6645,11 @@ static inline void *mas_first_entry(struct ma_state *mas, struct maple_node *mn,
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);
@ -6635,13 +6669,13 @@ static inline void *mas_first_entry(struct ma_state *mas, struct maple_node *mn,
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;