[Qemu-devel] [PATCH] vnc: fix segfault in closed connection handling

[Klim Kireev]

On one of our client's node, due to trying to read from closed ioc,
a segmentation fault occured. Corresponding backtrace:

Having analyzed the coredump, I understood that the reason is that
ioc_tag is reset on vnc_disconnect_start and ioc is cleaned
in vnc_disconnect_finish. Between these two events due to some
reasons the ioc_tag was set again and after vnc_disconnect_finish
the handler is running with freed ioc,
which led to the segmentation fault.

I suggest to check ioc_tag in vnc_disconnect_finish to prevent such
an occurrence.

Signed-off-by: Klim Kireev <address@hidden>
---
 ui/vnc.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/ui/vnc.c b/ui/vnc.c
index 33b087221f..b8bf0180cb 100644
--- a/ui/vnc.c
+++ b/ui/vnc.c
@@ -1270,6 +1270,10 @@ void vnc_disconnect_finish(VncState *vs)
     }
     g_free(vs->lossy_rect);
 
+    if (vs->ioc_tag) {
+        g_source_remove(vs->ioc_tag);
+        vs->ioc_tag = 0;
+    }
     object_unref(OBJECT(vs->ioc));
     vs->ioc = NULL;
     object_unref(OBJECT(vs->sioc));
-- 
2.14.3