Commit 8fba0fc7b3de ("selftests: tc: Add generic erspan_opts matching support for tc-flower") started triggering the following kmemleak warning: unreferenced object 0xffff888015fb0e00 (size 512): comm "softirq", pid 0, jiffies 4294679065 hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 40 d2 85 9e ff ff ff ff ........@....... 41 69 59 9d ff ff ff ff 00 00 00 00 00 00 00 00 AiY............. backtrace (crc 30b71e8b): __kmalloc_noprof+0x359/0x460 metadata_dst_alloc+0x28/0x490 erspan_rcv+0x4f1/0x1160 [ip_gre] gre_rcv+0x217/0x240 [ip_gre] gre_rcv+0x1b8/0x400 [gre] ip_protocol_deliver_rcu+0x31d/0x3a0 ip_local_deliver_finish+0x37d/0x620 ip_local_deliver+0x174/0x460 ip_rcv+0x52b/0x6b0 __netif_receive_skb_one_core+0x149/0x1a0 process_backlog+0x3c8/0x1390 __napi_poll.constprop.0+0xa1/0x390 net_rx_action+0x59b/0xe00 handle_softirqs+0x22b/0x630 do_softirq+0xb1/0xf0 __local_bh_enable_ip+0x115/0x150 vrf_ip6_input_dst unconditionally sets skb dst entry, add a call to skb_dst_drop to drop any existing entry. Cc: David Ahern Fixes: 9ff74384600a ("net: vrf: Handle ipv6 multicast and link-local addresses") Signed-off-by: Stanislav Fomichev --- drivers/net/vrf.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/net/vrf.c b/drivers/net/vrf.c index 9a4beea6ee0c..3ccd649913b5 100644 --- a/drivers/net/vrf.c +++ b/drivers/net/vrf.c @@ -1302,6 +1302,8 @@ static void vrf_ip6_input_dst(struct sk_buff *skb, struct net_device *vrf_dev, struct net *net = dev_net(vrf_dev); struct rt6_info *rt6; + skb_dst_drop(skb); + rt6 = vrf_ip6_route_lookup(net, vrf_dev, &fl6, ifindex, skb, RT6_LOOKUP_F_HAS_SADDR | RT6_LOOKUP_F_IFACE); if (unlikely(!rt6)) -- 2.50.1 Add WARN_ON_ONCE with CONFIG_NET_DEBUG to warn on overriding referenced dst entries. This should get a better signal than tracing leaked objects from kmemleak. Signed-off-by: Stanislav Fomichev --- include/linux/skbuff.h | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 5520524c93bf..c89931ac01e5 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -1159,6 +1159,12 @@ static inline struct dst_entry *skb_dst(const struct sk_buff *skb) return (struct dst_entry *)(skb->_skb_refdst & SKB_DST_PTRMASK); } +static inline void skb_dst_check(struct sk_buff *skb) +{ + DEBUG_NET_WARN_ON_ONCE(skb_dst(skb) && + !(skb->_skb_refdst & SKB_DST_NOREF)); +} + /** * skb_dst_set - sets skb dst * @skb: buffer @@ -1169,6 +1175,7 @@ static inline struct dst_entry *skb_dst(const struct sk_buff *skb) */ static inline void skb_dst_set(struct sk_buff *skb, struct dst_entry *dst) { + skb_dst_check(skb); skb->slow_gro |= !!dst; skb->_skb_refdst = (unsigned long)dst; } @@ -1185,6 +1192,7 @@ static inline void skb_dst_set(struct sk_buff *skb, struct dst_entry *dst) */ static inline void skb_dst_set_noref(struct sk_buff *skb, struct dst_entry *dst) { + skb_dst_check(skb); WARN_ON(!rcu_read_lock_held() && !rcu_read_lock_bh_held()); skb->slow_gro |= !!dst; skb->_skb_refdst = (unsigned long)dst | SKB_DST_NOREF; -- 2.50.1