From: Ignacy Gawędzki Date: Tue, 3 Feb 2015 18:05:18 +0000 (+0100) Subject: cls_api.c: Fix dumping of non-existing actions' stats. X-Git-Tag: firefly_0821_release~176^2~2421^2~8 X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=b057df24a7536cce6c372efe9d0e3d1558afedf4;p=firefly-linux-kernel-4.4.55.git cls_api.c: Fix dumping of non-existing actions' stats. In tcf_exts_dump_stats(), ensure that exts->actions is not empty before accessing the first element of that list and calling tcf_action_copy_stats() on it. This fixes some random segvs when adding filters of type "basic" with no particular action. This also fixes the dumping of those "no-action" filters, which more often than not made calls to tcf_action_copy_stats() fail and consequently netlink attributes added by the caller to be removed by a call to nla_nest_cancel(). Fixes: 33be62715991 ("net_sched: act: use standard struct list_head") Signed-off-by: Ignacy Gawędzki Acked-by: Cong Wang Signed-off-by: David S. Miller --- diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c index aad6a679fb13..baef987fe2c0 100644 --- a/net/sched/cls_api.c +++ b/net/sched/cls_api.c @@ -556,8 +556,9 @@ void tcf_exts_change(struct tcf_proto *tp, struct tcf_exts *dst, } EXPORT_SYMBOL(tcf_exts_change); -#define tcf_exts_first_act(ext) \ - list_first_entry(&(exts)->actions, struct tc_action, list) +#define tcf_exts_first_act(ext) \ + list_first_entry_or_null(&(exts)->actions, \ + struct tc_action, list) int tcf_exts_dump(struct sk_buff *skb, struct tcf_exts *exts) { @@ -603,7 +604,7 @@ int tcf_exts_dump_stats(struct sk_buff *skb, struct tcf_exts *exts) { #ifdef CONFIG_NET_CLS_ACT struct tc_action *a = tcf_exts_first_act(exts); - if (tcf_action_copy_stats(skb, a, 1) < 0) + if (a != NULL && tcf_action_copy_stats(skb, a, 1) < 0) return -1; #endif return 0;