uci: fix a potential use-after-free in uci_set()

[project/uci.git] / list.c

diff --git a/list.c b/list.c
index 0347138..25aec56 100644 (file)
--- a/list.c
+++ b/list.c
@@ -12,8 +12,9 @@
  * GNU Lesser General Public License for more details.
  */
 
-static void uci_list_set_pos(struct uci_list *head, struct uci_list *ptr, int pos)
+static bool uci_list_set_pos(struct uci_list *head, struct uci_list *ptr, int pos)
 {
+       struct uci_list *old_head = ptr->prev;
        struct uci_list *new_head = head;
        struct uci_element *p = NULL;
 
@@ -25,6 +26,8 @@ static void uci_list_set_pos(struct uci_list *head, struct uci_list *ptr, int po
        }
 
        uci_list_add(new_head->next, ptr);
+
+       return (old_head != new_head);
 }
 
 static inline void uci_list_fixup(struct uci_list *ptr)
@@ -514,12 +517,13 @@ int uci_reorder_section(struct uci_context *ctx, struct uci_section *s, int pos)
 {
        struct uci_package *p = s->package;
        bool internal = ctx && ctx->internal;
+       bool changed = false;
        char order[32];
 
        UCI_HANDLE_ERR(ctx);
 
-       uci_list_set_pos(&s->package->sections, &s->e.list, pos);
-       if (!internal && p->has_delta) {
+       changed = uci_list_set_pos(&s->package->sections, &s->e.list, pos);
+       if (!internal && p->has_delta && changed) {
                sprintf(order, "%d", pos);
                uci_add_delta(ctx, &p->delta, UCI_CMD_REORDER, s->e.name, NULL, order);
        }
@@ -695,11 +699,15 @@ int uci_set(struct uci_context *ctx, struct uci_ptr *ptr)
                ptr->s = uci_alloc_section(ptr->p, ptr->value, ptr->section);
                ptr->last = &ptr->s->e;
        } else if (ptr->o && ptr->option) { /* update option */
+               struct uci_option *o;
+
                if ((ptr->o->type == UCI_TYPE_STRING) &&
                        !strcmp(ptr->o->v.string, ptr->value))
                        return 0;
-               uci_free_option(ptr->o);
+
+               o = ptr->o;
                ptr->o = uci_alloc_option(ptr->s, ptr->option, ptr->value);
+               uci_free_option(o);
                ptr->last = &ptr->o->e;
        } else if (ptr->s && ptr->section) { /* update section */
                char *s = uci_strdup(ctx, ptr->value);