From 5d325decca71baface7d14316ed83509ac0ccb32 Mon Sep 17 00:00:00 2001
From: Seth Hoenig <shoenig@duck.com>
Date: Tue, 14 Feb 2023 15:09:43 -0600
Subject: [PATCH] cgutil: handle panic from runc helper method (#16180)

This PR wraps the cgroups.IsCgroup2UnifiedMode() helper method from
runc in a defer/recover block because it might panic in some cases.

Upstream fix in: https://github.com/opencontainers/runc/pull/3745

Closes #16179
---
 .changelog/16180.txt              |  3 +++
 client/lib/cgutil/cgutil_linux.go | 14 +++++++++++++-
 2 files changed, 16 insertions(+), 1 deletion(-)
 create mode 100644 .changelog/16180.txt

diff --git a/.changelog/16180.txt b/.changelog/16180.txt
new file mode 100644
index 000000000..265d62404
--- /dev/null
+++ b/.changelog/16180.txt
@@ -0,0 +1,3 @@
+```release-note:bug
+cgutil: handle panic coming from runc helper method
+```
diff --git a/client/lib/cgutil/cgutil_linux.go b/client/lib/cgutil/cgutil_linux.go
index 178b65b7b..84ce6b408 100644
--- a/client/lib/cgutil/cgutil_linux.go
+++ b/client/lib/cgutil/cgutil_linux.go
@@ -18,7 +18,19 @@ import (
 // cgroups.v1
 //
 // This is a read-only value.
-var UseV2 = cgroups.IsCgroup2UnifiedMode()
+var UseV2 = safelyDetectUnifiedMode()
+
+// Currently it is possible for the runc utility function to panic
+// https://github.com/opencontainers/runc/pull/3745
+func safelyDetectUnifiedMode() (result bool) {
+	defer func() {
+		if r := recover(); r != nil {
+			result = false
+		}
+	}()
+	result = cgroups.IsCgroup2UnifiedMode()
+	return
+}
 
 // GetCgroupParent returns the mount point under the root cgroup in which Nomad
 // will create cgroups. If parent is not set, an appropriate name for the version