From 4e2ad53ababeaac44d71162650984abfe783960c Mon Sep 17 00:00:00 2001 From: Peng Zhang Date: Sat, 6 May 2023 10:47:52 +0800 Subject: [PATCH] maple_tree: fix potential out-of-bounds access in mas_wr_end_piv() commit cd00dd2585c4158e81fdfac0bbcc0446afbad26d upstream. Check the write offset end bounds before using it as the offset into the pivot array. This avoids a possible out-of-bounds access on the pivot array if the write extends to the last slot in the node, in which case the node maximum should be used as the end pivot. akpm: this doesn't affect any current callers, but new users of mapletree may encounter this problem if backported into earlier kernels, so let's fix it in -stable kernels in case of this. Link: https://lkml.kernel.org/r/20230506024752.2550-1-zhangpeng.00@bytedance.com Fixes: 54a611b60590 ("Maple Tree: add new data structure") Signed-off-by: Peng Zhang Reviewed-by: Liam R. Howlett Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- lib/maple_tree.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/lib/maple_tree.c b/lib/maple_tree.c index b72268848ade..2f1f661157c9 100644 --- a/lib/maple_tree.c +++ b/lib/maple_tree.c @@ -4281,11 +4281,13 @@ static inline bool mas_wr_slot_store(struct ma_wr_state *wr_mas) static inline void mas_wr_end_piv(struct ma_wr_state *wr_mas) { - while ((wr_mas->mas->last > wr_mas->end_piv) && - (wr_mas->offset_end < wr_mas->node_end)) - wr_mas->end_piv = wr_mas->pivots[++wr_mas->offset_end]; + while ((wr_mas->offset_end < wr_mas->node_end) && + (wr_mas->mas->last > wr_mas->pivots[wr_mas->offset_end])) + wr_mas->offset_end++; - if (wr_mas->mas->last > wr_mas->end_piv) + if (wr_mas->offset_end < wr_mas->node_end) + wr_mas->end_piv = wr_mas->pivots[wr_mas->offset_end]; + else wr_mas->end_piv = wr_mas->mas->max; } @@ -4442,7 +4444,6 @@ static inline void *mas_wr_store_entry(struct ma_wr_state *wr_mas) } /* At this point, we are at the leaf node that needs to be altered. */ - wr_mas->end_piv = wr_mas->r_max; mas_wr_end_piv(wr_mas); if (!wr_mas->entry)