| Message ID | 20230411041005.26205-1-zhangpeng.00@bytedance.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v2,1/2] maple_tree: Fix a potential memory leak, OOB access, or other unpredictable bug | expand |
* 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 >
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;
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> --- lib/maple_tree.c | 19 +++++++------------ 1 file changed, 7 insertions(+), 12 deletions(-)