[PATCH 5.4 23/90] net/tls: Fix sk_psock refcnt leak in bpf_exec_tx_verdict()

From: Greg Kroah-Hartman
Date: Wed May 13 2020 - 06:03:39 EST


From: Xiyu Yang <xiyuyang19@xxxxxxxxxxxx>

[ Upstream commit 095f5614bfe16e5b3e191b34ea41b10d6fdd4ced ]

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

When bpf_exec_tx_verdict() 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
bpf_exec_tx_verdict(). When "policy" equals to NULL 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 this error path before
bpf_exec_tx_verdict() returns.

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 | 2 ++
1 file changed, 2 insertions(+)

--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -797,6 +797,8 @@ static int bpf_exec_tx_verdict(struct sk
*copied -= sk_msg_free(sk, msg);
tls_free_open_rec(sk);
}
+ if (psock)
+ sk_psock_put(sk, psock);
return err;
}
more_data: