linux-kernel - [PATCH 5.4 24/90] net/tls: Fix sk_psock refcnt leak when in tls_data

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Message-Id: <20200513094411.176123869@linuxfoundation.org>
Date:   Wed, 13 May 2020 11:44:20 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Xiyu Yang <xiyuyang19@...an.edu.cn>,
        Xin Tan <tanxin.ctf@...il.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 5.4 24/90] net/tls: Fix sk_psock refcnt leak when in tls_data_ready()

From: Xiyu Yang <xiyuyang19@...an.edu.cn>

[ Upstream commit 62b4011fa7bef9fa00a6aeec26e69685dc1cc21e ]

tls_data_ready() invokes sk_psock_get(), which returns a reference of
the specified sk_psock object to "psock" with increased refcnt.

When tls_data_ready() returns, local variable "psock" becomes invalid,
so the refcount should be decreased to keep refcount balanced.

The reference counting issue happens in one exception handling path of
tls_data_ready(). When "psock->ingress_msg" is empty but "psock" is not
NULL, the function forgets to decrease the refcnt increased by
sk_psock_get(), causing a refcnt leak.

Fix this issue by calling sk_psock_put() on all paths when "psock" is
not NULL.

Signed-off-by: Xiyu Yang <xiyuyang19@...an.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@...il.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/tls/tls_sw.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -2078,8 +2078,9 @@ static void tls_data_ready(struct sock *
 	strp_data_ready(&ctx->strp);

 	psock = sk_psock_get(sk);
-	if (psock && !list_empty(&psock->ingress_msg)) {
-		ctx->saved_data_ready(sk);
+	if (psock) {
+		if (!list_empty(&psock->ingress_msg))
+			ctx->saved_data_ready(sk);
 		sk_psock_put(sk, psock);
 	}
 }