diff options
| author | John Fastabend <john.fastabend@gmail.com> | 2014-10-06 08:28:52 +0400 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2014-10-07 02:02:33 +0400 |
| commit | 18cdb37ebf4c986d9502405cbd16b0ac29770c25 (patch) | |
| tree | 2bf659bf5d527447c11845ca06d15d1b69b9ab31 /net/sched/cls_fw.c | |
| parent | 13990f8156862fe945a1a226850a6550c8988a33 (diff) | |
| download | linux-18cdb37ebf4c986d9502405cbd16b0ac29770c25.tar.xz | |
net: sched: do not use tcf_proto 'tp' argument from call_rcu
Using the tcf_proto pointer 'tp' from inside the classifiers callback
is not valid because it may have been cleaned up by another call_rcu
occuring on another CPU.
'tp' is currently being used by tcf_unbind_filter() in this patch we
move instances of tcf_unbind_filter outside of the call_rcu() context.
This is safe to do because any running schedulers will either read the
valid class field or it will be zeroed.
And all schedulers today when the class is 0 do a lookup using the
same call used by the tcf_exts_bind(). So even if we have a running
classifier hit the null class pointer it will do a lookup and get
to the same result. This is particularly fragile at the moment because
the only way to verify this is to audit the schedulers call sites.
Reported-by: Cong Wang <xiyou.wangconf@gmail.com>
Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Acked-by: Cong Wang <cwang@twopensource.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/sched/cls_fw.c')
| -rw-r--r-- | net/sched/cls_fw.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/net/sched/cls_fw.c b/net/sched/cls_fw.c index da805aeeb65c..dbfdfd1f1a9f 100644 --- a/net/sched/cls_fw.c +++ b/net/sched/cls_fw.c @@ -123,9 +123,7 @@ static int fw_init(struct tcf_proto *tp) static void fw_delete_filter(struct rcu_head *head) { struct fw_filter *f = container_of(head, struct fw_filter, rcu); - struct tcf_proto *tp = f->tp; - tcf_unbind_filter(tp, &f->res); tcf_exts_destroy(&f->exts); kfree(f); } @@ -143,6 +141,7 @@ static void fw_destroy(struct tcf_proto *tp) while ((f = rtnl_dereference(head->ht[h])) != NULL) { RCU_INIT_POINTER(head->ht[h], rtnl_dereference(f->next)); + tcf_unbind_filter(tp, &f->res); call_rcu(&f->rcu, fw_delete_filter); } } @@ -166,6 +165,7 @@ static int fw_delete(struct tcf_proto *tp, unsigned long arg) fp = &pfp->next, pfp = rtnl_dereference(*fp)) { if (pfp == f) { RCU_INIT_POINTER(*fp, rtnl_dereference(f->next)); + tcf_unbind_filter(tp, &f->res); call_rcu(&f->rcu, fw_delete_filter); return 0; } @@ -280,6 +280,7 @@ static int fw_change(struct net *net, struct sk_buff *in_skb, RCU_INIT_POINTER(fnew->next, rtnl_dereference(pfp->next)); rcu_assign_pointer(*fp, fnew); + tcf_unbind_filter(tp, &f->res); call_rcu(&f->rcu, fw_delete_filter); *arg = (unsigned long)fnew; |