From e9be5dabf256c18a5575d1394e481e4f21ece97d Mon Sep 17 00:00:00 2001
From: Sage Weil <sage@redhat.com>
Date: Tue, 7 Aug 2018 17:02:56 -0500
Subject: [PATCH] kv/KeyValueDB: return const char* from MergeOperator::name()

This avoids a c_str() on a temporary string later down the line, which
avoids a use-after-free.

Fixes: http://tracker.ceph.com/issues/26875
Signed-off-by: Sage Weil <sage@redhat.com>
---
 src/kv/KeyValueDB.h                       | 2 +-
 src/kv/RocksDBStore.cc                    | 2 +-
 src/os/bluestore/BitmapFreelistManager.cc | 2 +-
 src/os/bluestore/BlueStore.cc             | 2 +-
 src/test/objectstore/test_kv.cc           | 2 +-
 5 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/kv/KeyValueDB.h b/src/kv/KeyValueDB.h
index a3fbe2fd54050..097fe12827804 100644
--- a/src/kv/KeyValueDB.h
+++ b/src/kv/KeyValueDB.h
@@ -447,7 +447,7 @@ public:
       const char *rdata, size_t rlen,
       std::string *new_value) = 0;
     /// We use each operator name and each prefix to construct the overall RocksDB operator name for consistency check at open time.
-    virtual string name() const = 0;
+    virtual const char *name() const = 0;
 
     virtual ~MergeOperator() {}
   };
diff --git a/src/kv/RocksDBStore.cc b/src/kv/RocksDBStore.cc
index a19d84de73569..e2fef5d3823de 100644
--- a/src/kv/RocksDBStore.cc
+++ b/src/kv/RocksDBStore.cc
@@ -128,7 +128,7 @@ public:
   explicit MergeOperatorLinker(const std::shared_ptr<KeyValueDB::MergeOperator> &o) : mop(o) {}
 
   const char *Name() const override {
-    return mop->name().c_str();
+    return mop->name();
   }
 
   bool Merge(const rocksdb::Slice& key,
diff --git a/src/os/bluestore/BitmapFreelistManager.cc b/src/os/bluestore/BitmapFreelistManager.cc
index 5270dbc9e2010..27af4c75c4aae 100644
--- a/src/os/bluestore/BitmapFreelistManager.cc
+++ b/src/os/bluestore/BitmapFreelistManager.cc
@@ -35,7 +35,7 @@ struct XorMergeOperator : public KeyValueDB::MergeOperator {
   }
   // We use each operator name and each prefix to construct the
   // overall RocksDB operator name for consistency check at open time.
-  string name() const override {
+  const char *name() const override {
     return "bitwise_xor";
   }
 };
diff --git a/src/os/bluestore/BlueStore.cc b/src/os/bluestore/BlueStore.cc
index 42318ab811143..2b2386509f19a 100644
--- a/src/os/bluestore/BlueStore.cc
+++ b/src/os/bluestore/BlueStore.cc
@@ -560,7 +560,7 @@ struct Int64ArrayMergeOperator : public KeyValueDB::MergeOperator {
   }
   // We use each operator name and each prefix to construct the
   // overall RocksDB operator name for consistency check at open time.
-  string name() const override {
+  const char *name() const override {
     return "int64_array";
   }
 };
diff --git a/src/test/objectstore/test_kv.cc b/src/test/objectstore/test_kv.cc
index 407cee5d929ca..c47a29299bc43 100644
--- a/src/test/objectstore/test_kv.cc
+++ b/src/test/objectstore/test_kv.cc
@@ -208,7 +208,7 @@ struct AppendMOP : public KeyValueDB::MergeOperator {
   }
   // We use each operator name and each prefix to construct the
   // overall RocksDB operator name for consistency check at open time.
-  string name() const override {
+  const char *name() const override {
     return "Append";
   }
 };
-- 
2.39.5