@@ -241,7 +241,8 @@ static struct publication *tipc_service_insert_publ(struct net *net,
static struct publication *tipc_service_remove_publ(struct net *net,
struct tipc_service *sc,
u32 lower, u32 upper,
- u32 node, u32 key)
+ u32 node, u32 key,
+ struct service_range **rng)
{
struct tipc_subscription *sub, *tmp;
struct service_range *sr;
@@ -275,19 +276,15 @@ static struct publication *tipc_service_remove_publ(struct net *net,
list_del(&p->all_publ);
list_del(&p->local_publ);
-
- /* Remove service range item if this was its last publication */
- if (list_empty(&sr->all_publ)) {
+ if (list_empty(&sr->all_publ))
last = true;
- rb_erase(&sr->tree_node, &sc->ranges);
- kfree(sr);
- }
/* Notify any waiting subscriptions */
list_for_each_entry_safe(sub, tmp, &sc->subscriptions, service_list) {
tipc_sub_report_overlap(sub, p->lower, p->upper, TIPC_WITHDRAWN,
p->port, p->node, p->scope, last);
}
+ *rng = sr;
return p;
}
@@ -379,13 +376,20 @@ struct publication *tipc_nametbl_remove_publ(struct net *net, u32 type,
u32 node, u32 key)
{
struct tipc_service *sc = tipc_service_find(net, type);
+ struct service_range *sr = NULL;
struct publication *p = NULL;
if (!sc)
return NULL;
spin_lock_bh(&sc->lock);
- p = tipc_service_remove_publ(net, sc, lower, upper, node, key);
+ p = tipc_service_remove_publ(net, sc, lower, upper, node, key, &sr);
+
+ /* Remove service range item if this was its last publication */
+ if (sr && list_empty(&sr->all_publ)) {
+ rb_erase(&sr->tree_node, &sc->ranges);
+ kfree(sr);
+ }
/* Delete service item if this no more publications and subscriptions */
if (RB_EMPTY_ROOT(&sc->ranges) && list_empty(&sc->subscriptions)) {
@@ -747,16 +751,17 @@ int tipc_nametbl_init(struct net *net)
static void tipc_service_delete(struct net *net, struct tipc_service *sc)
{
struct service_range *sr, *tmpr;
- struct publication *p, *tmpb;
+ struct publication *p, *tmp;
spin_lock_bh(&sc->lock);
rbtree_postorder_for_each_entry_safe(sr, tmpr, &sc->ranges, tree_node) {
- list_for_each_entry_safe(p, tmpb,
- &sr->all_publ, all_publ) {
+ list_for_each_entry_safe(p, tmp, &sr->all_publ, all_publ) {
tipc_service_remove_publ(net, sc, p->lower, p->upper,
- p->node, p->key);
+ p->node, p->key, &sr);
kfree_rcu(p, rcu);
}
+ rb_erase(&sr->tree_node, &sc->ranges);
+ kfree(sr);
}
hlist_del_init_rcu(&sc->service_list);
spin_unlock_bh(&sc->lock);
When we delete a service item in tipc_nametbl_stop() we loop over all service ranges in the service's RB tree, and for each service range we loop over its pertaining publications while calling tipc_service_remove_publ() for each of them. However, tipc_service_remove_publ() has the side effect that it also removes the comprising service range item when there are no publications left. This leads to a "use-after-free" access when the inner loop continues to the next iteration, since the range item holding the list we are looping no longer exists. We fix this by moving the delete of the service range item outside the said function. Instead, we now let the two functions calling it test if the list is empty and perform the removal when that is the case. Reported-by: syzbot+d64b64afc55660106556@syzkaller.appspotmail.com Signed-off-by: Jon Maloy <jon.maloy@ericsson.com> --- net/tipc/name_table.c | 29 +++++++++++++++++------------ 1 file changed, 17 insertions(+), 12 deletions(-)