From: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx> commit 06e8fd999334bcd76b4d72d7b9206d4aea89764e upstream. 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> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- lib/maple_tree.c | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-) --- a/lib/maple_tree.c +++ b/lib/maple_tree.c @@ -5064,10 +5064,10 @@ 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)) { @@ -5075,13 +5075,15 @@ 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)
