* Peng Zhang zhangpeng.00@bytedance.com [230411 00:10]:

In mas_alloc_nodes(), "node->node_count = 0" means to initialize the node_count field of the new node, but the node may not be a new node. It may be a node that existed before and node_count has a value, setting it to 0 will cause a memory leak. At this time, mas->alloc->total will be greater than the actual number of nodes in the linked list, which may cause many other errors. For example, out-of-bounds access in mas_pop_node(), and mas_pop_node() may return addresses that should not be used. Fix it by initializing node_count only for new nodes.

Also, by the way, an if-else statement was removed to simplify the code.

Fixes: 54a611b60590 ("Maple Tree: add new data structure") Signed-off-by: Peng Zhang zhangpeng.00@bytedance.com Cc: stable@vger.kernel.org

Reviewed-by: Liam R. Howlett Liam.Howlett@oracle.com

---

lib/maple_tree.c | 19 +++++++------------ 1 file changed, 7 insertions(+), 12 deletions(-)

diff --git a/lib/maple_tree.c b/lib/maple_tree.c index dd1a114d9e2b..938634bea2d6 100644 --- a/lib/maple_tree.c +++ b/lib/maple_tree.c @@ -1303,26 +1303,21 @@ static inline void mas_alloc_nodes(struct ma_state *mas, gfp_t gfp) node = mas->alloc; node->request_count = 0; while (requested) {

• max_req = MAPLE_ALLOC_SLOTS;
  

• if (node->node_count) {
  

• 	unsigned int offset = node->node_count;
  

• 	slots = (void **)&node->slot[offset];
  

• 	max_req -= offset;
  

• } else {
  

• 	slots = (void **)&node->slot;
  

• }
  

• max_req = MAPLE_ALLOC_SLOTS - node->node_count;
  

• slots = (void **)&node->slot[node->node_count];
  

  max_req = min(requested, max_req); count = mt_alloc_bulk(gfp, max_req, slots); if (!count) goto nomem_bulk;

• if (node->node_count == 0) {
  

• 	node->slot[0]->node_count = 0;
  

• 	node->slot[0]->request_count = 0;
  

• }
  

• node->node_count += count; allocated += count; node = node->slot[0];

• node->node_count = 0;
  

• node->request_count = 0;
  

  requested -= count; } mas->alloc->total = allocated;

-- 2.20.1