[RFC PATCH 1/6] hv_sock: Check hv_pkt_iter_first_raw()'s return value

[Andrea Parri (Microsoft)]

The function returns NULL if the ring buffer has no enough space
available for a packet descriptor.  The ring buffer's write_index
is in memory which is shared with the Hyper-V host, its value is
thus subject to being changed at any time.

Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@xxxxxxxxx>
---
 net/vmw_vsock/hyperv_transport.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/vmw_vsock/hyperv_transport.c b/net/vmw_vsock/hyperv_transport.c
index e111e13b66604..943352530936e 100644
--- a/net/vmw_vsock/hyperv_transport.c
+++ b/net/vmw_vsock/hyperv_transport.c
@@ -603,6 +603,8 @@ static ssize_t hvs_stream_dequeue(struct vsock_sock *vsk, struct msghdr *msg,
 
 	if (need_refill) {
 		hvs->recv_desc = hv_pkt_iter_first_raw(hvs->chan);
+		if (!hvs->recv_desc)
+			return -ENOBUFS;
 		ret = hvs_update_recv_data(hvs);
 		if (ret)
 			return ret;
-- 
2.25.1