From e30f2bd21e463d5f5f9f9210b75193a0257b8a8c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marko=20M=C3=A4kel=C3=A4?= <marko.makela@mariadb.com>
Date: Thu, 10 Sep 2026 10:13:28 +0300
Subject: [PATCH] MDEV-41021 SET GLOBAL innodb_log_archive ignores read-only
 mode

log_t::set_archive(): Prevent a crash in log_t::header_rewrite()
by refusing the operation if the log is read-only.
---
 mysql-test/suite/innodb/r/log_archive.result | 2 ++
 mysql-test/suite/innodb/t/log_archive.test   | 2 ++
 storage/innobase/log/log0log.cc              | 6 ++++++
 3 files changed, 10 insertions(+)

diff --git a/mysql-test/suite/innodb/r/log_archive.result b/mysql-test/suite/innodb/r/log_archive.result
index 3bc20f3c2fc..6f12acda34b 100644
--- a/mysql-test/suite/innodb/r/log_archive.result
+++ b/mysql-test/suite/innodb/r/log_archive.result
@@ -50,6 +50,8 @@ ALTER TABLE mysql.innodb_table_stats ROW_FORMAT=COMPACT, ALGORITHM=INPLACE;
 ERROR 0A000: ALGORITHM=INPLACE is not supported. Reason: Running in read-only mode. Try ALGORITHM=COPY
 TRUNCATE TABLE mysql.innodb_table_stats;
 ERROR HY000: Table 'innodb_table_stats' is read only
+SET GLOBAL innodb_log_archive=!@@GLOBAL.innodb_log_archive;
+ERROR HY000: InnoDB is in read only mode
 # restart: --innodb-log-recovery-start=0 --innodb-log-recovery-target=18446744073705357290
 SELECT variable_name, variable_value FROM information_schema.global_status
 WHERE variable_name LIKE 'INNODB_LSN%';
diff --git a/mysql-test/suite/innodb/t/log_archive.test b/mysql-test/suite/innodb/t/log_archive.test
index 282a0676c1e..925108880ba 100644
--- a/mysql-test/suite/innodb/t/log_archive.test
+++ b/mysql-test/suite/innodb/t/log_archive.test
@@ -148,6 +148,8 @@ DROP TABLE mysql.innodb_index_stats;
 ALTER TABLE mysql.innodb_table_stats ROW_FORMAT=COMPACT, ALGORITHM=INPLACE;
 --error ER_OPEN_AS_READONLY
 TRUNCATE TABLE mysql.innodb_table_stats;
+--error ER_INNODB_READ_ONLY
+SET GLOBAL innodb_log_archive=!@@GLOBAL.innodb_log_archive;
 
 --source include/shutdown_mysqld.inc
 --move_file $DATADIR/ib_logfile0 $DATADIR/ib_ffffffffff803000.log
diff --git a/storage/innobase/log/log0log.cc b/storage/innobase/log/log0log.cc
index ae236359328..5f4a59b41fc 100644
--- a/storage/innobase/log/log0log.cc
+++ b/storage/innobase/log/log0log.cc
@@ -767,6 +767,12 @@ void log_t::header_rewrite(my_bool archive) noexcept
 @param thd      SQL connection */
 void log_t::set_archive(my_bool archive, THD *thd) noexcept
 {
+  if (UNIV_UNLIKELY(recv_sys.rpo != 0))
+  {
+    my_error(ER_INNODB_READ_ONLY, MYF(0));
+    return;
+  }
+
   thd_wait_begin(thd, THD_WAIT_DISKIO);
   tpool::tpool_wait_begin();
   lsn_t wait_lsn;