[PATCH 5.13 513/800] udp: Fix a memory leak in udp_read_sock()

[Greg Kroah-Hartman]

From: Cong Wang <cong.wang@xxxxxxxxxxxxx>

[ Upstream commit e00a5c331bf57f41fcfdc5da4f5caeafe5e54c1d ]

sk_psock_verdict_recv() clones the skb and uses the clone
afterward, so udp_read_sock() should free the skb after using
it, regardless of error or not.

This fixes a real kmemleak.

Fixes: d7f571188ecf ("udp: Implement ->read_sock() for sockmap")
Signed-off-by: Cong Wang <cong.wang@xxxxxxxxxxxxx>
Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Acked-by: John Fastabend <john.fastabend@xxxxxxxxx>
Acked-by: Jakub Sitnicki <jakub@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/bpf/20210615021342.7416-4-xiyou.wangcong@xxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 net/ipv4/udp.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 1307ad0d3b9e..8091276cb85b 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;
 	}
-- 
2.30.2