From beac59b37a8b0ea834904870e5c236d2627947a2 Mon Sep 17 00:00:00 2001
From: Ian Gudger <igudger@google.com>
Date: Wed, 3 Oct 2018 20:21:25 -0700
Subject: Fix panic if FIOASYNC callback is registered and triggered without
 target

PiperOrigin-RevId: 215674589
Change-Id: I4f8871b64c570dc6da448d2fe351cec8a406efeb
---
 pkg/sentry/kernel/fasync/fasync.go | 5 +++++
 1 file changed, 5 insertions(+)

(limited to 'pkg/sentry/kernel/fasync')

diff --git a/pkg/sentry/kernel/fasync/fasync.go b/pkg/sentry/kernel/fasync/fasync.go
index 7d01abe90..f77339cae 100644
--- a/pkg/sentry/kernel/fasync/fasync.go
+++ b/pkg/sentry/kernel/fasync/fasync.go
@@ -60,6 +60,11 @@ func (a *FileAsync) Callback(e *waiter.Entry) {
 	if tg != nil {
 		t = tg.Leader()
 	}
+	if t == nil {
+		// No recipient has been registered.
+		a.mu.Unlock()
+		return
+	}
 	c := t.Credentials()
 	// Logic from sigio_perm in fs/fcntl.c.
 	if a.requester.EffectiveKUID == 0 ||
-- 
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