[PATCH 5.6 032/118] net/tls: Fix sk_psock refcnt leak when in tls_data_ready()

From: Greg Kroah-Hartman
Date: Wed May 13 2020 - 05:54:16 EST


From: Xiyu Yang <xiyuyang19@xxxxxxxxxxxx>

[ 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@xxxxxxxxxxxx>
Signed-off-by: Xin Tan <tanxin.ctf@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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
@@ -2083,8 +2083,9 @@ 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);
}
}