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[PULL,1/3] event_notifier: prevent accidental use after close

Message ID 1490750257-19907-2-git-send-email-mst@redhat.com
State New
Headers show

Commit Message

Michael S. Tsirkin March 29, 2017, 1:18 a.m. UTC 
From: Halil Pasic <pasic@linux.vnet.ibm.com>

Let's set the handles to the underlying facilities to their extremal
value so no accidental misuse can happen, and to make it obvious that the
notifier is dysfunctional. E.g. if we just close an fd but do not touch
the int holding the fd eventually a read/write could succeed again when
the fd gets reused, and corrupt the file addressed by the fd.

Signed-off-by: Halil Pasic <pasic@linux.vnet.ibm.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 util/event_notifier-posix.c | 2 ++
 util/event_notifier-win32.c | 1 +
 2 files changed, 3 insertions(+)
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Patch

diff --git a/util/event_notifier-posix.c b/util/event_notifier-posix.c
index 7e40252..acdbe3b 100644
--- a/util/event_notifier-posix.c
+++ b/util/event_notifier-posix.c
@@ -81,8 +81,10 @@  void event_notifier_cleanup(EventNotifier *e)
 {
     if (e->rfd != e->wfd) {
         close(e->rfd);
+        e->rfd = -1;
     }
     close(e->wfd);
+    e->wfd = -1;
 }
 
 int event_notifier_get_fd(const EventNotifier *e)
diff --git a/util/event_notifier-win32.c b/util/event_notifier-win32.c
index 519fb59..62c53b0 100644
--- a/util/event_notifier-win32.c
+++ b/util/event_notifier-win32.c
@@ -25,6 +25,7 @@  int event_notifier_init(EventNotifier *e, int active)
 void event_notifier_cleanup(EventNotifier *e)
 {
     CloseHandle(e->event);
+    e->event = NULL;
 }
 
 HANDLE event_notifier_get_handle(EventNotifier *e)