* Peng Zhang <zhangpeng.00@xxxxxxxxxxxxx> [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@xxxxxxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx>
> ---
> 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 += count;
> allocated += count;
> node = node->slot[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
>
