From 7a408dbdf40930144c1bad654cb1e31e5ce5fc7a Mon Sep 17 00:00:00 2001 From: Jon Olav Hauglid Date: Thu, 22 Jan 2015 14:19:56 +0100 Subject: Bug#19770858: MYSQLD CAN BE DRIVEN TO OOM WITH TWO SIMPLE SESSION VARS The problem was that the maximum value of the transaction_prealloc_size session system variable was ULONG_MAX which meant that it was possible to cause the server to allocate excessive amounts of memory. This patch fixes the problem by reducing the maxmimum value of transaction_prealloc_size and transaction_alloc_block_size down to 128K. Note that transactions will still be able to allocate more than 128K if needed, this patch just reduces the amount that can be preallocated - as well as the maximum size of the incremental allocation blocks. --- sql/sys_vars.cc | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'sql/sys_vars.cc') diff --git a/sql/sys_vars.cc b/sql/sys_vars.cc index e826624b42f..d1c02cda20c 100644 --- a/sql/sys_vars.cc +++ b/sql/sys_vars.cc @@ -1,4 +1,4 @@ -/* Copyright (c) 2002, 2014, Oracle and/or its affiliates. All rights reserved. +/* Copyright (c) 2002, 2015, Oracle and/or its affiliates. All rights reserved. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -1836,7 +1836,7 @@ static Sys_var_ulong Sys_trans_alloc_block_size( "transaction_alloc_block_size", "Allocation block size for transactions to be stored in binary log", SESSION_VAR(trans_alloc_block_size), CMD_LINE(REQUIRED_ARG), - VALID_RANGE(1024, ULONG_MAX), DEFAULT(QUERY_ALLOC_BLOCK_SIZE), + VALID_RANGE(1024, 128 * 1024 * 1024), DEFAULT(QUERY_ALLOC_BLOCK_SIZE), BLOCK_SIZE(1024), NO_MUTEX_GUARD, NOT_IN_BINLOG, ON_CHECK(0), ON_UPDATE(fix_trans_mem_root)); @@ -1844,7 +1844,7 @@ static Sys_var_ulong Sys_trans_prealloc_size( "transaction_prealloc_size", "Persistent buffer for transactions to be stored in binary log", SESSION_VAR(trans_prealloc_size), CMD_LINE(REQUIRED_ARG), - VALID_RANGE(1024, ULONG_MAX), DEFAULT(TRANS_ALLOC_PREALLOC_SIZE), + VALID_RANGE(1024, 128 * 1024 * 1024), DEFAULT(TRANS_ALLOC_PREALLOC_SIZE), BLOCK_SIZE(1024), NO_MUTEX_GUARD, NOT_IN_BINLOG, ON_CHECK(0), ON_UPDATE(fix_trans_mem_root)); -- cgit v1.2.1