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[bpf,v3,3/8] udp: fix a memory leak in udp_read_sock()

Message ID 20210527011155.10097-4-xiyou.wangcong@gmail.com (mailing list archive)
State Changes Requested
Delegated to: BPF
Headers show
Series sock_map: some bug fixes and improvements | expand

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netdev/build_32bit success Errors and warnings before: 7 this patch: 7
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netdev/build_allmodconfig_warn success Errors and warnings before: 7 this patch: 7
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Commit Message

Cong Wang May 27, 2021, 1:11 a.m. UTC 
From: Cong Wang <cong.wang@bytedance.com>

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")
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Jakub Sitnicki <jakub@cloudflare.com>
Cc: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
---
 net/ipv4/udp.c | 2 ++
 1 file changed, 2 insertions(+)
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Patch

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;
 	}