lkml.org 
[lkml]   [2011]   [Sep]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
SubjectRe: [PATCH] fib:fix BUG_ON in fib_nl_newrule when add new fib rule
From
Date
Le dimanche 11 septembre 2011 à 01:19 +0800, Wanlong Gao a écrit :
> From: Gao feng <gaofeng@cn.fujitsu.com>
>
> add new fib rule can cause BUG_ON
> the reproduce shell is
>
> #ip rule add pref 38
> #ip rule add pref 38
> #ip rule add to 192.168.3.0/24 goto 38
> #ip rule del pref 38
> #ip rule add to 192.168.3.0/24 goto 38
> #ip rule add pref 38
>
> then the BUG_ON will happen
> add a var unresolved in struct fib_rule
> and use it to identify whether this rule is unresolved
>
> Signed-off-by: Gao feng <gaofeng@cn.fujitsu.com>
> ---
> include/net/fib_rules.h | 1 +
> net/core/fib_rules.c | 5 ++++-
> 2 files changed, 5 insertions(+), 1 deletions(-)
>
> diff --git a/include/net/fib_rules.h b/include/net/fib_rules.h
> index 075f1e3..e4bae01 100644
> --- a/include/net/fib_rules.h
> +++ b/include/net/fib_rules.h
> @@ -19,6 +19,7 @@ struct fib_rule {
> u32 flags;
> u32 table;
> u8 action;
> + u8 unresolved;
> u32 target;
> struct fib_rule __rcu *ctarget;
> char iifname[IFNAMSIZ];
> diff --git a/net/core/fib_rules.c b/net/core/fib_rules.c
> index e7ab0c0..aa20560 100644
> --- a/net/core/fib_rules.c
> +++ b/net/core/fib_rules.c
> @@ -384,9 +384,11 @@ static int fib_nl_newrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
> */
> list_for_each_entry(r, &ops->rules_list, list) {
> if (r->action == FR_ACT_GOTO &&
> - r->target == rule->pref) {
> + r->target == rule->pref &&
> + r->unresolved) {
> BUG_ON(rtnl_dereference(r->ctarget) != NULL);
> rcu_assign_pointer(r->ctarget, rule);
> + r->unresolved = 0;
> if (--ops->unresolved_rules == 0)
> break;
> }
> @@ -488,6 +490,7 @@ static int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
> list_for_each_entry(tmp, &ops->rules_list, list) {
> if (rtnl_dereference(tmp->ctarget) == rule) {
> rcu_assign_pointer(tmp->ctarget, NULL);
> + tmp->unresolved = 1;
> ops->unresolved_rules++;
> }
> }

Hmm, good catch, but you add 'unresolved' field but dont init it
correctly to 1 in all cases.

Following will break :

ip rule add pref 100
ip rule add to 192.168.3.0/24 goto 200
ip rule add pref 200

Normally, we should have

unresolved = (ctarget == NULL);

What about following patch instead ?

diff --git a/net/core/fib_rules.c b/net/core/fib_rules.c
index e7ab0c0..3231b46 100644
--- a/net/core/fib_rules.c
+++ b/net/core/fib_rules.c
@@ -384,8 +384,8 @@ static int fib_nl_newrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
*/
list_for_each_entry(r, &ops->rules_list, list) {
if (r->action == FR_ACT_GOTO &&
- r->target == rule->pref) {
- BUG_ON(rtnl_dereference(r->ctarget) != NULL);
+ r->target == rule->pref &&
+ rtnl_dereference(r->ctarget) == NULL) {
rcu_assign_pointer(r->ctarget, rule);
if (--ops->unresolved_rules == 0)
break;

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2011-09-11 09:15    [W:0.067 / U:3.976 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site