* Peng Zhang zhangpeng.00@bytedance.com [230407 00:10]:
In mas_alloc_nodes(), there is such a piece of code: while (requested) { ... node->node_count = 0; ... }
You don't need to quote code in your commit message since it is available in the change log or in the file itself.
"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.
Fixes: 54a611b60590 ("Maple Tree: add new data structure") Signed-off-by: Peng Zhang zhangpeng.00@bytedance.com Cc: stable@vger.kernel.org
lib/maple_tree.c | 16 ++++------------ 1 file changed, 4 insertions(+), 12 deletions(-)
diff --git a/lib/maple_tree.c b/lib/maple_tree.c index 65fd861b30e1..9e25b3215803 100644 --- a/lib/maple_tree.c +++ b/lib/maple_tree.c @@ -1249,26 +1249,18 @@ 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];
Thanks, this is much cleaner.
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->node_count = 0;node->request_count = 0;
Why are we not clearing request_count anymore?
requested -= count;} mas->alloc->total = allocated; -- 2.20.1