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

From: John Fastabend <[email-masked]>
Date: Wed, 30 Jun 2021 14:53:48 -0700

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 <[email-masked]>
---
 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