From 6a7e4c21021d2a9900794fbaa5adc466262ec241 Mon Sep 17 00:00:00 2001
From: Lucas Manning <lucasmanning@google.com>
Date: Wed, 15 May 2024 10:52:17 -0700
Subject: [PATCH] Fix race during fdbased endpoint teardown.

If the fdbased processor is handling packets and the endpoint dispatcher
concurrently is set to nil we can crash the sandbox.

PiperOrigin-RevId: 634007307
---
 pkg/tcpip/link/fdbased/processors.go | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/pkg/tcpip/link/fdbased/processors.go b/pkg/tcpip/link/fdbased/processors.go
index 03b51fb4a..5e634b1b4 100644
--- a/pkg/tcpip/link/fdbased/processors.go
+++ b/pkg/tcpip/link/fdbased/processors.go
@@ -62,6 +62,12 @@ func (p *processor) deliverPackets() {
 	p.e.mu.RLock()
 	p.gro.Dispatcher = p.e.dispatcher
 	p.e.mu.RUnlock()
+	if p.gro.Dispatcher == nil {
+		p.mu.Lock()
+		p.pkts.Reset()
+		p.mu.Unlock()
+		return
+	}
 
 	p.mu.Lock()
 	for p.pkts.Len() > 0 {