From 8845553a81a427bf34ed8466913bc197943a3af6 Mon Sep 17 00:00:00 2001 From: unknown Date: Wed, 9 Jan 2008 00:40:41 +0300 Subject: [PATCH] Bug#33675: Usage of an uninitialized memory by filesort in a subquery caused server crash. The filesort implementation has an optimization for subquery execution which consists of reusing previously allocated buffers. In particular the call to the read_buffpek_from_file function might be skipped when a big enough buffer for buffer descriptors (buffpeks) is already allocated. Beside allocating memory for buffpeks this function fills allocated buffer with data read from disk. Skipping it might led to using an arbitrary memory as fields' data and finally to a crash. Now the read_buffpek_from_file function is always called. It allocates new buffer only when necessary, but always fill it with correct data. sql/filesort.cc: Bug#33675: Usage of an uninitialized memory by filesort in a subquery caused server crash.Now the read_buffpek_from_file function is always called. It allocates new buffer only when necessary, but always fill it with correct data. mysql-test/r/subselect.result: Added a test case for the bug#33675: Usage of an uninitialized memory by filesort in a subquery caused server crash. mysql-test/t/subselect.test: Added a test case for the bug#33675: Usage of an uninitialized memory by filesort in a subquery caused server crash. --- mysql-test/r/subselect.result | 9 +++++++++ mysql-test/t/subselect.test | 22 ++++++++++++++++++++++ sql/filesort.cc | 22 +++++++++++++--------- 3 files changed, 44 insertions(+), 9 deletions(-) diff --git a/mysql-test/r/subselect.result b/mysql-test/r/subselect.result index f6487ae3ddf..75df77b0790 100644 --- a/mysql-test/r/subselect.result +++ b/mysql-test/r/subselect.result @@ -4383,4 +4383,13 @@ SELECT 2 FROM t1 WHERE EXISTS ((SELECT 1 FROM t2 WHERE t1.a=t2.a) UNION ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'UNION (SELECT 1 FROM t2 WHERE t1.a = t2.a))' at line 2 DROP TABLE t1,t2; +create table t1(f11 int, f12 int); +create table t2(f21 int unsigned not null, f22 int, f23 varchar(10)); +insert into t1 values(1,1),(2,2), (3, 3); +set session sort_buffer_size= 33*1024; +select count(*) from t1 where f12 = +(select f22 from t2 where f22 = f12 order by f21 desc, f22, f23 limit 1); +count(*) +3 +drop table t1,t2; End of 5.0 tests. diff --git a/mysql-test/t/subselect.test b/mysql-test/t/subselect.test index ea080964058..88e4f683e9e 100644 --- a/mysql-test/t/subselect.test +++ b/mysql-test/t/subselect.test @@ -3230,4 +3230,26 @@ SELECT 2 FROM t1 WHERE EXISTS ((SELECT 1 FROM t2 WHERE t1.a=t2.a) UNION DROP TABLE t1,t2; +# +# Bug#33675: Usage of an uninitialized memory by filesort in a subquery +# caused server crash. +# +create table t1(f11 int, f12 int); +create table t2(f21 int unsigned not null, f22 int, f23 varchar(10)); +insert into t1 values(1,1),(2,2), (3, 3); +let $i=10000; +--disable_query_log +--disable_warnings +while ($i) +{ + eval insert into t2 values (-1 , $i/5000 + 1, '$i'); + dec $i; +} +--enable_warnings +--enable_query_log +set session sort_buffer_size= 33*1024; +select count(*) from t1 where f12 = +(select f22 from t2 where f22 = f12 order by f21 desc, f22, f23 limit 1); + +drop table t1,t2; --echo End of 5.0 tests. diff --git a/sql/filesort.cc b/sql/filesort.cc index 08ffa2211fa..5a8e3627758 100644 --- a/sql/filesort.cc +++ b/sql/filesort.cc @@ -37,7 +37,8 @@ if (my_b_write((file),(byte*) (from),param->ref_length)) \ static char **make_char_array(char **old_pos, register uint fields, uint length, myf my_flag); -static BUFFPEK *read_buffpek_from_file(IO_CACHE *buffer_file, uint count); +static byte *read_buffpek_from_file(IO_CACHE *buffer_file, uint count, + byte *buf); static ha_rows find_all_keys(SORTPARAM *param,SQL_SELECT *select, uchar * *sort_keys, IO_CACHE *buffer_file, IO_CACHE *tempfile,IO_CACHE *indexfile); @@ -238,9 +239,10 @@ ha_rows filesort(THD *thd, TABLE *table, SORT_FIELD *sortorder, uint s_length, } else { - if (!table_sort.buffpek && table_sort.buffpek_len < maxbuffer && - !(table_sort.buffpek= - (byte *) read_buffpek_from_file(&buffpek_pointers, maxbuffer))) + if (!(table_sort.buffpek= + read_buffpek_from_file(&buffpek_pointers, maxbuffer, + (table_sort.buffpek_len < maxbuffer ? + NULL : table_sort.buffpek)))) goto err; buffpek= (BUFFPEK *) table_sort.buffpek; table_sort.buffpek_len= maxbuffer; @@ -368,18 +370,20 @@ static char **make_char_array(char **old_pos, register uint fields, /* Read 'count' number of buffer pointers into memory */ -static BUFFPEK *read_buffpek_from_file(IO_CACHE *buffpek_pointers, uint count) +static byte *read_buffpek_from_file(IO_CACHE *buffpek_pointers, uint count, + byte *buf) { - ulong length; - BUFFPEK *tmp; + ulong length= sizeof(BUFFPEK)*count; + byte *tmp= buf; DBUG_ENTER("read_buffpek_from_file"); if (count > UINT_MAX/sizeof(BUFFPEK)) return 0; /* sizeof(BUFFPEK)*count will overflow */ - tmp=(BUFFPEK*) my_malloc(length=sizeof(BUFFPEK)*count, MYF(MY_WME)); + if (!tmp) + tmp= (byte *)my_malloc(length, MYF(MY_WME)); if (tmp) { if (reinit_io_cache(buffpek_pointers,READ_CACHE,0L,0,0) || - my_b_read(buffpek_pointers, (byte*) tmp, length)) + my_b_read(buffpek_pointers, tmp, length)) { my_free((char*) tmp, MYF(0)); tmp=0;