From 0ee4977c301e634640c45ff1745be707e2662a97 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Sat, 23 Oct 2010 09:44:25 +0000 Subject: [PATCH] fib: fix fib_nl_newrule() Some panic reports in fib_rules_lookup() show a rule could have a NULL pointer as a next pointer in the rules_list. This can actually happen because of a bug in fib_nl_newrule() : It checks if current rule is the destination of unresolved gotos. (Other rules have gotos to this about to be inserted rule) Problem is it does the resolution of the gotos before the rule is inserted in the rules_list (and has a valid next pointer) Fix this by moving the rules_list insertion before the changes on gotos. A lockless reader can not any more follow a ctarget pointer, unless destination is ready (has a valid next pointer) Reported-by: Oleg A. Arkhangelsky Reported-by: Joe Buehler Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/core/fib_rules.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/net/core/fib_rules.c b/net/core/fib_rules.c index 1bc3f253ba6c7..12b43cc2f889d 100644 --- a/net/core/fib_rules.c +++ b/net/core/fib_rules.c @@ -373,6 +373,11 @@ static int fib_nl_newrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg) fib_rule_get(rule); + if (last) + list_add_rcu(&rule->list, &last->list); + else + list_add_rcu(&rule->list, &ops->rules_list); + if (ops->unresolved_rules) { /* * There are unresolved goto rules in the list, check if @@ -395,11 +400,6 @@ static int fib_nl_newrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg) if (unresolved) ops->unresolved_rules++; - if (last) - list_add_rcu(&rule->list, &last->list); - else - list_add_rcu(&rule->list, &ops->rules_list); - notify_rule_change(RTM_NEWRULE, rule, ops, nlh, NETLINK_CB(skb).pid); flush_route_cache(ops); rules_ops_put(ops); -- 2.39.5