# \[Patch bpf\] udp: fix a memory leak in udp\_read\_sock()

- From: Cong Wang \<hidden\>
- Date: 2021-05-17 02:23:42 
- List: netdev
- Page: https://ratatoskr.run/netdev/2021/05/7768819
- Thread: https://ratatoskr.run/netdev/2021/05/7768819/t.md

```text
From: Cong Wang <redacted>

sk_psock_verdict_recv() clones the skb and uses the clone
afterward, so udp_read_sock() should free the original skb after
done using it.

Fixes: d7f571188ecf ("udp: Implement ->read_sock() for sockmap")
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Jakub Sitnicki <jakub@cloudflare.com>
Cc: Lorenz Bauer <redacted>
Signed-off-by: Cong Wang <redacted>
---
 net/ipv4/udp.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 15f5504adf5b..e31d67fd5183 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1798,11 +1798,13 @@ int udp_read_sock(struct sock *sk, read_descriptor_t *desc,
 		if (used <= 0) {
 			if (!copied)
 				copied = used;
+			kfree_skb(skb);
 			break;
 		} else if (used <= skb->len) {
 			copied += used;
 		}
 
+		kfree_skb(skb);
 		if (!desc->count)
 			break;
 	}
-- 
2.25.1

```