From 9b6605ec4c3ad6a6e5b6964b02a28d171a5802b5 Mon Sep 17 00:00:00 2001 From: Jan Venekamp Date: Sun, 20 Nov 2022 02:08:20 +0100 Subject: uci: fix use-after-free uci_set on update option When uci_set is called with ptr->o set and ptr->option = NULL, then in uci_expand_ptr ptr->option is set to ptr->o->e.name. This will result in use-after-free because ptr->option is used in the call to uci_add_delta after uci_free_option(ptr->o). Signed-off-by: Jan Venekamp --- list.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/list.c b/list.c index 24ed2ee..ac3686c 100644 --- a/list.c +++ b/list.c @@ -725,15 +725,16 @@ 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; + struct uci_option *old = ptr->o; if ((ptr->o->type == UCI_TYPE_STRING) && !strcmp(ptr->o->v.string, ptr->value)) return 0; - o = ptr->o; ptr->o = uci_alloc_option(ptr->s, ptr->option, ptr->value); - uci_free_option(o); + if (ptr->option == old->e.name) + ptr->option = ptr->o->e.name; + uci_free_option(old); ptr->last = &ptr->o->e; } else if (ptr->s && ptr->section) { /* update section */ char *s = uci_strdup(ctx, ptr->value); -- cgit v1.2.1