tcp_bpf_recvmsg() invokes sk_psock_get(), which returns a reference of
the specified sk_psock object to "psock" with increased refcnt.
When tcp_bpf_recvmsg() returns, local variable "psock" becomes invalid,
so the refcount should be decreased to keep refcount balanced.
The reference counting issue happens in several exception handling paths
of tcp_bpf_recvmsg(). When those error scenarios occur such as "flags"
includes MSG_ERRQUEUE, the function forgets to decrease the refcnt
increased by sk_psock_get(), causing a refcnt leak.
Fix this issue by calling sk_psock_put() when those error scenarios
occur.
Signed-off-by: Xiyu Yang <xiyuyang19@xxxxxxxxxxxx>
Signed-off-by: Xin Tan <tanxin.ctf@xxxxxxxxx>
---
net/ipv4/tcp_bpf.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c
index 5a05327f97c1..feb6b90672c1 100644
--- a/net/ipv4/tcp_bpf.c
+++ b/net/ipv4/tcp_bpf.c
@@ -265,11 +265,15 @@ static int tcp_bpf_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
psock = sk_psock_get(sk);
if (unlikely(!psock))
return tcp_recvmsg(sk, msg, len, nonblock, flags, addr_len);
- if (unlikely(flags & MSG_ERRQUEUE))
+ if (unlikely(flags & MSG_ERRQUEUE)) {
+ sk_psock_put(sk, psock);
return inet_recv_error(sk, msg, len, addr_len);
+ }
if (!skb_queue_empty(&sk->sk_receive_queue) &&
- sk_psock_queue_empty(psock))
+ sk_psock_queue_empty(psock)) {
+ sk_psock_put(sk, psock);
return tcp_recvmsg(sk, msg, len, nonblock, flags, addr_len);
+ }
lock_sock(sk);
msg_bytes_ready:
copied = __tcp_bpf_recvmsg(sk, psock, msg, len, flags);
--
2.7.4
