Prereq: "3.6.0"
diff -ur --new-file /var/tmp/postfix-3.6.0/src/global/mail_version.h ./src/global/mail_version.h
--- /var/tmp/postfix-3.6.0/src/global/mail_version.h	2021-04-29 12:13:09.000000000 -0400
+++ ./src/global/mail_version.h	2021-06-13 14:50:57.000000000 -0400
@@ -20,8 +20,8 @@
   * Patches change both the patchlevel and the release date. Snapshots have no
   * patchlevel; they change the release date only.
   */
-#define MAIL_RELEASE_DATE	"20210429"
-#define MAIL_VERSION_NUMBER	"3.6.0"
+#define MAIL_RELEASE_DATE	"20210613"
+#define MAIL_VERSION_NUMBER	"3.6.1"
 
 #ifdef SNAPSHOT
 #define MAIL_VERSION_DATE	"-" MAIL_RELEASE_DATE
diff -ur --new-file /var/tmp/postfix-3.6.0/HISTORY ./HISTORY
--- /var/tmp/postfix-3.6.0/HISTORY	2021-04-29 16:11:42.000000000 -0400
+++ ./HISTORY	2021-06-13 14:47:56.000000000 -0400
@@ -25557,3 +25557,17 @@
 20210428
 
 	Documentation: update by Paul Menzel. File: proto/SASL_README.html.
+
+20210601
+
+	Bugfix (introduced: Postfix 2.11): the command "postmap
+	lmdb:/file/name" handled duplicate keys ungracefully,
+	discarding entries stored up to and including the duplicate
+	key, and causing a double free() call with lmdb versions
+	0.9.17 and later. Reported by Adi Prasaja; double free()
+	root cause analysis by Howard Chu. File: util/slmdb.c.
+
+20210609
+
+	Typo (introduced: Postfix 3.4): silent_discard should be
+	silent-discard. File: proto/BDAT_README.html.
diff -ur --new-file /var/tmp/postfix-3.6.0/README_FILES/BDAT_README ./README_FILES/BDAT_README
--- /var/tmp/postfix-3.6.0/README_FILES/BDAT_README	2020-08-29 13:52:25.000000000 -0400
+++ ./README_FILES/BDAT_README	2021-06-13 14:51:55.000000000 -0400
@@ -23,7 +23,7 @@
         # The logging alternative:
         smtpd_discard_ehlo_keywords = chunking
         # The non-logging alternative:
-        smtpd_discard_ehlo_keywords = chunking, silent_discard
+        smtpd_discard_ehlo_keywords = chunking, silent-discard
 
 Specify '-o smtpd_discard_ehlo_keywords=' in master.cf for the submission and
 smtps services, if you have clients that benefit from CHUNKING support.
diff -ur --new-file /var/tmp/postfix-3.6.0/html/BDAT_README.html ./html/BDAT_README.html
--- /var/tmp/postfix-3.6.0/html/BDAT_README.html	2020-08-29 13:52:15.000000000 -0400
+++ ./html/BDAT_README.html	2021-06-13 14:51:55.000000000 -0400
@@ -51,7 +51,7 @@
     # The logging alternative:
     <a href="postconf.5.html#smtpd_discard_ehlo_keywords">smtpd_discard_ehlo_keywords</a> = chunking
     # The non-logging alternative:
-    <a href="postconf.5.html#smtpd_discard_ehlo_keywords">smtpd_discard_ehlo_keywords</a> = chunking, silent_discard
+    <a href="postconf.5.html#smtpd_discard_ehlo_keywords">smtpd_discard_ehlo_keywords</a> = chunking, silent-discard
 </pre>
 </blockquote>
 
diff -ur --new-file /var/tmp/postfix-3.6.0/proto/BDAT_README.html ./proto/BDAT_README.html
--- /var/tmp/postfix-3.6.0/proto/BDAT_README.html	2020-08-29 13:51:42.000000000 -0400
+++ ./proto/BDAT_README.html	2021-06-09 08:46:08.000000000 -0400
@@ -51,7 +51,7 @@
     # The logging alternative:
     smtpd_discard_ehlo_keywords = chunking
     # The non-logging alternative:
-    smtpd_discard_ehlo_keywords = chunking, silent_discard
+    smtpd_discard_ehlo_keywords = chunking, silent-discard
 </pre>
 </blockquote>
 
diff -ur --new-file /var/tmp/postfix-3.6.0/src/util/slmdb.c ./src/util/slmdb.c
--- /var/tmp/postfix-3.6.0/src/util/slmdb.c	2017-02-18 20:58:21.000000000 -0500
+++ ./src/util/slmdb.c	2021-06-01 17:02:52.000000000 -0400
@@ -386,12 +386,16 @@
      * - With a bulk-mode transaction we commit when the database is closed.
      */
     if (slmdb->open_flags & O_TRUNC) {
-	if ((status = mdb_drop(slmdb->txn, slmdb->dbi, 0)) != 0)
+	if ((status = mdb_drop(slmdb->txn, slmdb->dbi, 0)) != 0) {
+	    mdb_txn_abort(slmdb->txn);
+	    slmdb->txn = 0;
 	    return (status);
+	}
 	if ((slmdb->slmdb_flags & SLMDB_FLAG_BULK) == 0) {
-	    if ((status = mdb_txn_commit(slmdb->txn)) != 0)
-		return (status);
+	    status = mdb_txn_commit(slmdb->txn);
 	    slmdb->txn = 0;
+	    if (status != 0)
+		return (status);
 	}
     } else if ((slmdb->lmdb_flags & MDB_RDONLY) != 0
 	       || (slmdb->slmdb_flags & SLMDB_FLAG_BULK) == 0) {
@@ -582,11 +586,15 @@
      * Do the update.
      */
     if ((status = mdb_put(txn, slmdb->dbi, mdb_key, mdb_value, flags)) != 0) {
-	mdb_txn_abort(txn);
 	if (status != MDB_KEYEXIST) {
+	    mdb_txn_abort(txn);
 	    if ((status = slmdb_recover(slmdb, status)) == 0)
 		status = slmdb_put(slmdb, mdb_key, mdb_value, flags);
 	    SLMDB_API_RETURN(slmdb, status);
+	} else {
+	    /* Abort non-bulk transaction only. */
+	    if (slmdb->txn == 0)
+		mdb_txn_abort(txn);
 	}
     }