cadence_gem: switch to use qemu_receive_packet() for loopback

Fix CVE-2021-3416

This patch switches to use qemu_receive_packet() which can detect
reentrancy and return early.

This is intended to address CVE-2021-3416.

Cc: Prasad J Pandit <ppandit@redhat.com>
Cc: qemu-stable@nongnu.org
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
Signed-off-by: Jason Wang <jasowang@redhat.com>

Signed-off-by: Jiajie Li <lijiajie11@huawei.com>

cadence_gem-switch-to-use-qemu_receive_packet-for-lo.patch

@@ -0,0 +1,44 @@
+From 22aa1e5315508da1ce8ec4565bbf2e525e79c6c2 Mon Sep 17 00:00:00 2001
+From: Alexander Bulekov <alxndr@bu.edu>
+Date: Fri, 14 May 2021 10:39:58 +0800
+Subject: [PATCH] cadence_gem: switch to use qemu_receive_packet() for loopback
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Fix CVE-2021-3416
+
+This patch switches to use qemu_receive_packet() which can detect
+reentrancy and return early.
+
+This is intended to address CVE-2021-3416.
+
+Cc: Prasad J Pandit <ppandit@redhat.com>
+Cc: qemu-stable@nongnu.org
+Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
+Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
+Signed-off-by: Jason Wang <jasowang@redhat.com>
+
+Signed-off-by: Jiajie Li <lijiajie11@huawei.com>
+---
+ hw/net/cadence_gem.c | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/hw/net/cadence_gem.c b/hw/net/cadence_gem.c
+index d412085884..52205f36be 100644
+--- a/hw/net/cadence_gem.c
++++ b/hw/net/cadence_gem.c
+@@ -1221,8 +1221,8 @@ static void gem_transmit(CadenceGEMState *s)
+                 /* Send the packet somewhere */
+                 if (s->phy_loop || (s->regs[GEM_NWCTRL] &
+                                     GEM_NWCTRL_LOCALLOOP)) {
+-                    gem_receive(qemu_get_queue(s->nic), tx_packet,
+-                                total_bytes);
++                    qemu_receive_packet(qemu_get_queue(s->nic), tx_packet,
++                                        total_bytes);
+                 } else {
+                     qemu_send_packet(qemu_get_queue(s->nic), tx_packet,
+                                      total_bytes);
+-- 
+2.27.0
+