From a08855f30bb24990b17266333d3828dea10bdc87 Mon Sep 17 00:00:00 2001
From: Edwin Rodriguez <edwin.rodriguez1@ibm.com>
Date: Thu, 7 Aug 2025 14:27:18 -0400
Subject: [PATCH] mds/MDSMap: Enhance set_min_compat_client to validate
 iterator range before sorting feature bits

Fixes: https://tracker.ceph.com/issues/72476
Signed-off-by: Edwin Rodriguez <edwin.rodriguez1@ibm.com>
---
 src/mds/MDSMap.cc | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/mds/MDSMap.cc b/src/mds/MDSMap.cc
index 59f9c5a4da0..f7cec0e1a7b 100644
--- a/src/mds/MDSMap.cc
+++ b/src/mds/MDSMap.cc
@@ -1331,7 +1331,14 @@ void MDSMap::set_min_compat_client(ceph_release_t version)
   else if (version >= ceph_release_t::jewel)
     bits.push_back(CEPHFS_FEATURE_JEWEL);
 
-  std::sort(bits.begin(), bits.end());
+  if (bits.size() >= 2) {  // Need at least 2 elements to sort
+    auto first = bits.begin();
+    auto last = bits.end();
+    if (first < last) {  // Validate iterator range
+      std::sort(first, last);
+    }
+  }
+
   required_client_features = feature_bitset_t(bits);
 }
 
-- 
2.39.5