From a1176791ab74bed2df83e7528fcde16a7c888420 Mon Sep 17 00:00:00 2001 From: Peng Zhang Date: Tue, 11 Apr 2023 12:10:04 +0800 Subject: maple_tree: fix a potential memory leak, OOB access, or other unpredictable bug commit 1f5f12ece722aacea1769fb644f27790ede339dc upstream. 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. Link: https://lkml.kernel.org/r/20230411041005.26205-1-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 | 19 +++++++------------ 1 file changed, 7 insertions(+), 12 deletions(-) (limited to 'lib/maple_tree.c') diff --git a/lib/maple_tree.c b/lib/maple_tree.c index f026d5fb51ab..9fe25ce9937b 100644 --- a/lib/maple_tree.c +++ b/lib/maple_tree.c @@ -1293,26 +1293,21 @@ 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; -- cgit v1.2.3