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authorJohn Fastabend <john.fastabend@gmail.com>2014-10-06 08:28:52 +0400
committerDavid S. Miller <davem@davemloft.net>2014-10-07 02:02:33 +0400
commit18cdb37ebf4c986d9502405cbd16b0ac29770c25 (patch)
tree2bf659bf5d527447c11845ca06d15d1b69b9ab31 /net/sched/cls_bpf.c
parent13990f8156862fe945a1a226850a6550c8988a33 (diff)
downloadlinux-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_bpf.c')
-rw-r--r--net/sched/cls_bpf.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/net/sched/cls_bpf.c b/net/sched/cls_bpf.c
index 4318d067b0a0..eed49d1d0878 100644
--- a/net/sched/cls_bpf.c
+++ b/net/sched/cls_bpf.c
@@ -92,7 +92,6 @@ static int cls_bpf_init(struct tcf_proto *tp)
static void cls_bpf_delete_prog(struct tcf_proto *tp, struct cls_bpf_prog *prog)
{
- tcf_unbind_filter(tp, &prog->res);
tcf_exts_destroy(&prog->exts);
bpf_prog_destroy(prog->filter);
@@ -116,6 +115,7 @@ static int cls_bpf_delete(struct tcf_proto *tp, unsigned long arg)
list_for_each_entry(prog, &head->plist, link) {
if (prog == todel) {
list_del_rcu(&prog->link);
+ tcf_unbind_filter(tp, &prog->res);
call_rcu(&prog->rcu, __cls_bpf_delete_prog);
return 0;
}
@@ -131,6 +131,7 @@ static void cls_bpf_destroy(struct tcf_proto *tp)
list_for_each_entry_safe(prog, tmp, &head->plist, link) {
list_del_rcu(&prog->link);
+ tcf_unbind_filter(tp, &prog->res);
call_rcu(&prog->rcu, __cls_bpf_delete_prog);
}
@@ -282,6 +283,7 @@ static int cls_bpf_change(struct net *net, struct sk_buff *in_skb,
if (oldprog) {
list_replace_rcu(&prog->link, &oldprog->link);
+ tcf_unbind_filter(tp, &oldprog->res);
call_rcu(&oldprog->rcu, __cls_bpf_delete_prog);
} else {
list_add_rcu(&prog->link, &head->plist);