[PATCH] net: sched: fix a use-after-free error on chain on the error exit path

[Colin King]

From: Colin Ian King <colin.k...@canonical.com>

Set chain to null after the call to tcf_chain_destroy so that we don't
call tcf_chain_put on the error exit path, thus avoiding a use-after-free
error.

Detected by CoverityScan, CID#1436357 ("Use after free")

Signed-off-by: Colin Ian King <colin.k...@canonical.com>
---
 net/sched/cls_api.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index 4020b8d932a1..82ebdc3fcb2e 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -511,6 +511,7 @@ static int tc_ctl_tfilter(struct sk_buff *skb, struct 
nlmsghdr *n,
        if (n->nlmsg_type == RTM_DELTFILTER && prio == 0) {
                tfilter_notify_chain(net, skb, n, chain, RTM_DELTFILTER);
                tcf_chain_destroy(chain);
+               chain = NULL;
                err = 0;
                goto errout;
        }
-- 
2.11.0