libcnary: [BUGFIX] Set list->end to NULL when removing last and only element from list

This prevents a UaF in node_list_add. The issue became visible after removing
the last (and only) item from a PLIST_DICT or PLIST_ARRAY node, and then
adding a new item - the item will not make it into the actual dictionary or
array because the list->end pointer points to invalid memory, effectively
causing memory corruption.

1 files changed, 2 insertions, 0 deletions

diff --git a/libcnary/node_list.c b/libcnary/node_list.c
index a45457d..b0dca0a 100644
--- a/libcnary/node_list.c
+++ b/libcnary/node_list.c
@@ -142,6 +142,8 @@ int node_list_remove(node_list_t* list, node_t* node) {
                                 // we just removed the first element
                                 if (newnode) {
                                         newnode->prev = NULL;
+                                } else {
+                                        list->end = NULL;
                                 }
                                 list->begin = newnode;
                         }