[PATCH net v2] vrf: Drop existing dst reference in vrf_ip6_input_dst

Stanislav Fomichev
2025-07-23T22:46:27Z

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 <dsahern@kernel.org>
Fixes: 9ff74384600a ("net: vrf: Handle ipv6 multicast and link-local addresses")
Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>
---
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