server/reds: allow call to reds_agent_remove even if it is gone

The current assert(reds->agent_state.connected) tiggers if when
the agent disconnected there was still data waiting to be sent (for
instance if there is a bug in the client handling clipboard and it
is killed while a large clipboard transfer is in progress). So first
call to reds_agent_remove happens from spice_server_char_device_remove_interface,
and then it is called again (triggering the assert) from free_item_data
from read_from_vdi_port because of the channel destruction.

Other option would be to not call it from one of the paths - but that
is suboptimal:
 * if there is no data in the pipe, the second call never happens.
 * the second call has to be there anyway, because it may fail during
  parsing data from the agent.

This patch fixes a segfault on this assert when a client starts passing
from guest agent to client a large clipboard and dies in the middle. There
is still another assert happening occasionally at marshaller which I don't
have a fix for (but it doesn't seem to be related).

1 files changed, 4 insertions, 4 deletions

diff --git a/server/reds.c b/server/reds.c
index 7845ebe7..508c8ff9 100644
--- a/server/reds.c
+++ b/server/reds.c
@@ -1095,16 +1095,17 @@ static void reds_agent_remove()
     SpiceCharDeviceInstance *sin = vdagent;
     SpiceCharDeviceInterface *sif;
 
+    if (!reds->agent_state.connected) {
+        return;
+    }
+    reds->agent_state.connected = 0;
     vdagent = NULL;
     reds_update_mouse_mode();
 
     if (!reds->peer || !sin) {
         return;
     }
-
-    ASSERT(reds->agent_state.connected)
     sif = SPICE_CONTAINEROF(sin->base.sif, SpiceCharDeviceInterface, base);
-    reds->agent_state.connected = 0;
     if (sif->state) {
         sif->state(sin, reds->agent_state.connected);
     }
@@ -1112,7 +1113,6 @@ static void reds_agent_remove()
     if (reds->mig_target) {
         return;
     }
-
     reds_reset_vdp();
     reds_send_agent_disconnected();
 }