MDEV-30106 InnoDB fails to validate the change buffer on startup

ibuf_init_at_db_start(): Validate the change buffer root page.
A later version may stop creating a change buffer, and this
validation check will prevent a downgrade from such later versions.

ibuf_max_size_update(): If the change buffer was not loaded, do nothing.

dict_boot(): Merge the local variable "error" to "err". Ignore
failures of ibuf_init_at_db_start() if innodb_force_recovery>=4.

mysql-test/suite/innodb/t/log_corruption.test

@@ -19,6 +19,7 @@ call mtr.add_suppression("InnoDB: Obtaining redo log encryption key version 1 fa
 call mtr.add_suppression("InnoDB: Decrypting checkpoint failed");
 call mtr.add_suppression("InnoDB: Are you sure you are using the right ib_logfile0 to start up the database\\? Log sequence number in the ib_logfile0 is 1213964,");
 call mtr.add_suppression("InnoDB: Log file .*ib_logfile1 is of different size 1048576 bytes than other log files 2097152 bytes!");
+call mtr.add_suppression("InnoDB: The change buffer is corrupted");
 --enable_query_log
 
 let bugdir= $MYSQLTEST_VARDIR/tmp/log_corruption;

storage/innobase/dict/dict0boot.cc

@@ -313,9 +313,9 @@ dict_boot(void)
 	dict_mem_index_add_field(index, "NAME", 0);
 
 	index->id = DICT_TABLES_ID;
-	dberr_t error = dict_index_add_to_cache(
+	dberr_t err = dict_index_add_to_cache(
 		index, mach_read_from_4(dict_hdr + DICT_HDR_TABLES));
-	ut_a(error == DB_SUCCESS);
+	ut_a(err == DB_SUCCESS);
 	ut_ad(!table->is_instant());
 	table->indexes.start->n_core_null_bytes = static_cast<uint8_t>(
 		UT_BITS_IN_BYTES(unsigned(table->indexes.start->n_nullable)));
@@ -325,9 +325,9 @@ dict_boot(void)
 	dict_mem_index_add_field(index, "ID", 0);
 
 	index->id = DICT_TABLE_IDS_ID;
-	error = dict_index_add_to_cache(
+	err = dict_index_add_to_cache(
 		index, mach_read_from_4(dict_hdr + DICT_HDR_TABLE_IDS));
-	ut_a(error == DB_SUCCESS);
+	ut_a(err == DB_SUCCESS);
 
 	/*-------------------------*/
 	table = dict_mem_table_create("SYS_COLUMNS", fil_system.sys_space,
@@ -355,9 +355,9 @@ dict_boot(void)
 	dict_mem_index_add_field(index, "POS", 0);
 
 	index->id = DICT_COLUMNS_ID;
-	error = dict_index_add_to_cache(
+	err = dict_index_add_to_cache(
 		index, mach_read_from_4(dict_hdr + DICT_HDR_COLUMNS));
-	ut_a(error == DB_SUCCESS);
+	ut_a(err == DB_SUCCESS);
 	ut_ad(!table->is_instant());
 	table->indexes.start->n_core_null_bytes = static_cast<uint8_t>(
 		UT_BITS_IN_BYTES(unsigned(table->indexes.start->n_nullable)));
@@ -398,9 +398,9 @@ dict_boot(void)
 	dict_mem_index_add_field(index, "ID", 0);
 
 	index->id = DICT_INDEXES_ID;
-	error = dict_index_add_to_cache(
+	err = dict_index_add_to_cache(
 		index, mach_read_from_4(dict_hdr + DICT_HDR_INDEXES));
-	ut_a(error == DB_SUCCESS);
+	ut_a(err == DB_SUCCESS);
 	ut_ad(!table->is_instant());
 	table->indexes.start->n_core_null_bytes = static_cast<uint8_t>(
 		UT_BITS_IN_BYTES(unsigned(table->indexes.start->n_nullable)));
@@ -427,9 +427,9 @@ dict_boot(void)
 	dict_mem_index_add_field(index, "POS", 0);
 
 	index->id = DICT_FIELDS_ID;
-	error = dict_index_add_to_cache(
+	err = dict_index_add_to_cache(
 		index, mach_read_from_4(dict_hdr + DICT_HDR_FIELDS));
-	ut_a(error == DB_SUCCESS);
+	ut_a(err == DB_SUCCESS);
 	ut_ad(!table->is_instant());
 	table->indexes.start->n_core_null_bytes = static_cast<uint8_t>(
 		UT_BITS_IN_BYTES(unsigned(table->indexes.start->n_nullable)));
@@ -440,9 +440,11 @@ dict_boot(void)
 
 	/* Initialize the insert buffer table and index for each tablespace */
 
-	dberr_t	err = ibuf_init_at_db_start();
+	err = ibuf_init_at_db_start();
 
-	if (err == DB_SUCCESS) {
+	if (err == DB_SUCCESS
+	    || srv_force_recovery >= SRV_FORCE_NO_IBUF_MERGE) {
+		err = DB_SUCCESS;
 		/* Load definitions of other indexes on system tables */
 
 		dict_load_sys_table(dict_sys.sys_tables);

storage/innobase/ibuf/ibuf0ibuf.cc

@@ -50,6 +50,7 @@ Created 7/19/1997 Heikki Tuuri
 #include "que0que.h"
 #include "srv0start.h" /* srv_shutdown_state */
 #include "rem0cmp.h"
+#include "log.h"
 
 /*	STRUCTURE OF AN INSERT BUFFER RECORD
 
@@ -408,35 +409,24 @@ ibuf_init_at_db_start(void)
 	ulint		n_used;
 
 	ut_ad(!ibuf.index);
+	dberr_t err;
 	mtr_t mtr;
 	mtr.start();
 	compile_time_assert(IBUF_SPACE_ID == TRX_SYS_SPACE);
 	compile_time_assert(IBUF_SPACE_ID == 0);
 	mtr_x_lock_space(fil_system.sys_space, &mtr);
-	buf_block_t* header_page = buf_page_get(
+	buf_block_t* header_page = buf_page_get_gen(
 		page_id_t(IBUF_SPACE_ID, FSP_IBUF_HEADER_PAGE_NO),
-		0, RW_X_LATCH, &mtr);
+		0, RW_X_LATCH, nullptr, BUF_GET,
+		__FILE__, __LINE__, &mtr, &err);
 
 	if (!header_page) {
+err_exit:
+		sql_print_error("InnoDB: The change buffer is corrupted");
 		mtr.commit();
-		return DB_DECRYPTION_FAILED;
+		return err;
 	}
 
-	/* At startup we intialize ibuf to have a maximum of
-	CHANGE_BUFFER_DEFAULT_SIZE in terms of percentage of the
-	buffer pool size. Once ibuf struct is initialized this
-	value is updated with the user supplied size by calling
-	ibuf_max_size_update(). */
-	ibuf.max_size = ((buf_pool_get_curr_size() >> srv_page_size_shift)
-			  * CHANGE_BUFFER_DEFAULT_SIZE) / 100;
-
-	mutex_create(LATCH_ID_IBUF, &ibuf_mutex);
-
-	mutex_create(LATCH_ID_IBUF_PESSIMISTIC_INSERT,
-		     &ibuf_pessimistic_insert_mutex);
-
-	mutex_enter(&ibuf_mutex);
-
 	fseg_n_reserved_pages(*header_page,
 			      IBUF_HEADER + IBUF_TREE_SEG_HEADER
 			      + header_page->frame, &n_used, &mtr);
@@ -448,15 +438,39 @@ ibuf_init_at_db_start(void)
 	{
 		buf_block_t*	block;
 
-		block = buf_page_get(
+		block = buf_page_get_gen(
 			page_id_t(IBUF_SPACE_ID, FSP_IBUF_TREE_ROOT_PAGE_NO),
-			0, RW_X_LATCH, &mtr);
+			0, RW_X_LATCH, nullptr, BUF_GET,
+			__FILE__, __LINE__, &mtr, &err);
+
+		if (!block) goto err_exit;
 
 		buf_block_dbg_add_level(block, SYNC_IBUF_TREE_NODE);
 
 		root = buf_block_get_frame(block);
 	}
 
+	if (page_is_comp(root) || fil_page_get_type(root) != FIL_PAGE_INDEX
+	    || btr_page_get_index_id(root) != DICT_IBUF_ID_MIN) {
+		err = DB_CORRUPTION;
+		goto err_exit;
+	}
+
+	/* At startup we initialize ibuf to have a maximum of
+	CHANGE_BUFFER_DEFAULT_SIZE in terms of percentage of the
+	buffer pool size. Once ibuf struct is initialized this
+	value is updated with the user supplied size by calling
+	ibuf_max_size_update(). */
+	ibuf.max_size = ((buf_pool_get_curr_size() >> srv_page_size_shift)
+			  * CHANGE_BUFFER_DEFAULT_SIZE) / 100;
+
+	mutex_create(LATCH_ID_IBUF, &ibuf_mutex);
+
+	mutex_create(LATCH_ID_IBUF_PESSIMISTIC_INSERT,
+		     &ibuf_pessimistic_insert_mutex);
+
+	mutex_enter(&ibuf_mutex);
+
 	ibuf_size_update(root);
 	mutex_exit(&ibuf_mutex);
 
@@ -507,6 +521,7 @@ ibuf_max_size_update(
 	ulint	new_val)	/*!< in: new value in terms of
 				percentage of the buffer pool size */
 {
+	if (UNIV_UNLIKELY(!ibuf.index)) return;
 	ulint	new_size = ((buf_pool_get_curr_size() >> srv_page_size_shift)
 			    * new_val) / 100;
 	mutex_enter(&ibuf_mutex);

storage/innobase/srv/srv0start.cc

@@ -2056,7 +2056,8 @@ void innodb_shutdown()
 	      || srv_force_recovery >= SRV_FORCE_NO_TRX_UNDO);
 	ut_ad(lock_sys.is_initialised() || !srv_was_started);
 	ut_ad(log_sys.is_initialised() || !srv_was_started);
-	ut_ad(ibuf.index || !srv_was_started);
+	ut_ad(ibuf.index || !srv_was_started
+	      || srv_force_recovery >= SRV_FORCE_NO_IBUF_MERGE);
 
 	dict_stats_deinit();