netdev - [PATCH bpf, sockmap 1/2] bpf, sockmap: fix potential memory leak on unlikely error case

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Date:   Wed, 30 Jun 2021 14:53:48 -0700
From:   John Fastabend <john.fastabend@...il.com>
To:     ast@...nel.org, daniel@...earbox.net, andriin@...com
Cc:     john.fastabend@...il.com, bpf@...r.kernel.org,
        netdev@...r.kernel.org
Subject: [PATCH bpf, sockmap 1/2] bpf, sockmap: fix potential memory leak on unlikely error case

If skb_linearize is needed and fails we could leak a msg on the error
handling. To fix ensure we kfree the msg block before returning error.
Found during code review.

Fixes: 4363023d2668e ("bpf, sockmap: Avoid failures from skb_to_sgvec when skb has frag_list")
Signed-off-by: John Fastabend <john.fastabend@...il.com>
---
 net/core/skmsg.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/core/skmsg.c b/net/core/skmsg.c
index 9b6160a191f8..22603289c2b2 100644
--- a/net/core/skmsg.c
+++ b/net/core/skmsg.c
@@ -505,8 +505,10 @@ static int sk_psock_skb_ingress_enqueue(struct sk_buff *skb,
 	 * drop the skb. We need to linearize the skb so that the mapping
 	 * in skb_to_sgvec can not error.
 	 */
-	if (skb_linearize(skb))
+	if (skb_linearize(skb)) {
+		kfree(msg);
 		return -EAGAIN;
+	}
 	num_sge = skb_to_sgvec(skb, msg->sg.data, 0, skb->len);
 	if (unlikely(num_sge < 0)) {
 		kfree(msg);
-- 
2.25.1