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| 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_basic.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_basic.c')
| -rw-r--r-- | net/sched/cls_basic.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/net/sched/cls_basic.c b/net/sched/cls_basic.c index 90647a8af8ca..cd61280941e5 100644 --- a/net/sched/cls_basic.c +++ b/net/sched/cls_basic.c @@ -91,9 +91,7 @@ static int basic_init(struct tcf_proto *tp) static void basic_delete_filter(struct rcu_head *head) { struct basic_filter *f = container_of(head, struct basic_filter, rcu); - struct tcf_proto *tp = f->tp; - tcf_unbind_filter(tp, &f->res); tcf_exts_destroy(&f->exts); tcf_em_tree_destroy(&f->ematches); kfree(f); @@ -106,6 +104,7 @@ static void basic_destroy(struct tcf_proto *tp) list_for_each_entry_safe(f, n, &head->flist, link) { list_del_rcu(&f->link); + tcf_unbind_filter(tp, &f->res); call_rcu(&f->rcu, basic_delete_filter); } RCU_INIT_POINTER(tp->root, NULL); @@ -120,6 +119,7 @@ static int basic_delete(struct tcf_proto *tp, unsigned long arg) list_for_each_entry(t, &head->flist, link) if (t == f) { list_del_rcu(&t->link); + tcf_unbind_filter(tp, &t->res); call_rcu(&t->rcu, basic_delete_filter); return 0; } @@ -222,6 +222,7 @@ static int basic_change(struct net *net, struct sk_buff *in_skb, if (fold) { list_replace_rcu(&fold->link, &fnew->link); + tcf_unbind_filter(tp, &fold->res); call_rcu(&fold->rcu, basic_delete_filter); } else { list_add_rcu(&fnew->link, &head->flist); |