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Subject[PATCH Fix 1/2] maple_tree: Fix underflow in mas_spanning_rebalance()
Date
When rebalancing a spanning store that spans the entire address space,
the big node end is not expanded the extra position that
mas_spanning_rebalance() expects. Fix this by expanding on such cases.
Also change mab_mas_cp() from assuming there are at least two entries to
ensure the correct metadata is written.

Fixes: f8acc5e9581e (Maple Tree: add new data structure)
Reported-by: Yu Zhao <yuzhao@google.com>
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
---
lib/maple_tree.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index a968948b3e3e..d8457122ca5d 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -1977,7 +1977,6 @@ static inline void mab_mas_cp(struct maple_big_node *b_node,
slots[mt_pivots[mt]] = NULL;

i = mab_start;
- pivots[j++] = b_node->pivot[i++];
do {
pivots[j++] = b_node->pivot[i++];
} while (i <= mab_end && likely(b_node->pivot[i]));
@@ -2970,7 +2969,7 @@ static int mas_spanning_rebalance(struct ma_state *mas,
mast->free = &free;
mast->destroy = &destroy;
l_mas.node = r_mas.node = m_mas.node = MAS_NONE;
- if (!mas_is_root_limits(mast->orig_l) &&
+ if (!(mast->orig_l->min && mast->orig_r->max == ULONG_MAX) &&
unlikely(mast->bn->b_end <= mt_min_slots[mast->bn->type]))
mast_spanning_rebalance(mast);

@@ -4004,6 +4003,9 @@ static inline int mas_wr_spanning_store(struct ma_wr_state *wr_mas)
if (r_mas.offset <= r_wr_mas.node_end)
mas_mab_cp(&r_mas, r_mas.offset, r_wr_mas.node_end,
&b_node, b_node.b_end + 1);
+ else
+ b_node.b_end++;
+
/* Stop spanning searches by searching for just index. */
l_mas.index = l_mas.last = mas->index;

--
2.35.1
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