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MDEV-41541 uninitialized memory read in optimizer replay

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init all frequencies - not all of them might be present in the replay
This commit is contained in:
Sergei Golubchik
2026-10-14 22:05:42 +02:00
parent 5ab51d6248
commit 4f4f76a83a
3 changed files with 80 additions and 1 deletions
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57
mysql-test/main/opt_context_load_stats_basic.result
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@@ -424,3 +424,60 @@ Warnings:
Warning 4269 Failed to parse saved optimizer context: "copy_cost" element not present at offset 631.
drop table t1;
drop database db1;
use test;
#
# MDEV-41541 uninitialized memory read in optimizer replay
#
create table t1 (a int, b int, index t1_idx_ab (a, b));
insert into t1 select seq%5, seq%8 from seq_1_to_20;
Warnings:
Warning 4269 Failed to parse saved optimizer context: "copy_cost" element not present at offset 631.
set session use_stat_tables='complementary';
analyze table t1 persistent for all;
Table Op Msg_type Msg_text
test.t1 analyze status Engine-independent statistics collected
test.t1 analyze status Table is already up to date
select a+1, b+1 from t1 limit 5;
a+1 b+1
1 3
1 5
1 6
1 8
2 1
Warnings:
Warning 4269 Failed to parse saved optimizer context: "copy_cost" element not present at offset 631.
select * from t1 where a<2 and b>4;
a b
0 5
0 7
1 6
Warnings:
Warning 4269 Failed to parse saved optimizer context: "copy_cost" element not present at offset 631.
set optimizer_record_context=ON;
select * from t1 where a<3 and b>6;
a b
0 7
2 7
Warnings:
Warning 4269 Failed to parse saved optimizer context: "copy_cost" element not present at offset 631.
set @opt_context=
(select REGEXP_SUBSTR(
context,
'(?<=set @opt_context=\')([\n\r].*)*(?=\'\;#opt_context_ends)')
from information_schema.optimizer_context);
set @opt_context_truncated= json_remove(@opt_context, '$.tables[0].indexes[0].rec_per_key[1]');
set optimizer_replay_context='opt_context_truncated';
select * from t1 where a<3 and b>6;
a b
0 7
2 7
set @opt_context=
(select REGEXP_SUBSTR(
context,
'(?<=set @opt_context=\')([\n\r].*)*(?=\'\;#opt_context_ends)')
from information_schema.optimizer_context);
select hex(json_extract(@opt_context, '$.tables[0].indexes[0].rec_per_key[1]') + 0.0);
hex(json_extract(@opt_context, '$.tables[0].indexes[0].rec_per_key[1]') + 0.0)
0
drop table t1;
# End of 13.1 tests

22
mysql-test/main/opt_context_load_stats_basic.test
View File

@@ -289,3 +289,25 @@ select * from t1 where a > 10;
drop table t1;
drop database db1;
use test;
--echo #
--echo # MDEV-41541 uninitialized memory read in optimizer replay
--echo #
create table t1 (a int, b int, index t1_idx_ab (a, b));
insert into t1 select seq%5, seq%8 from seq_1_to_20;
set session use_stat_tables='complementary';
analyze table t1 persistent for all;
select a+1, b+1 from t1 limit 5;
select * from t1 where a<2 and b>4;
set optimizer_record_context=ON;
select * from t1 where a<3 and b>6;
--source include/opt_context_save_in_var.inc
set @opt_context_truncated= json_remove(@opt_context, '$.tables[0].indexes[0].rec_per_key[1]');
set optimizer_replay_context='opt_context_truncated';
select * from t1 where a<3 and b>6;
--source include/opt_context_save_in_var.inc
select hex(json_extract(@opt_context, '$.tables[0].indexes[0].rec_per_key[1]') + 0.0);
drop table t1;
--echo # End of 13.1 tests

2
sql/opt_context_store_replay.cc
View File

@@ -1939,7 +1939,7 @@ void Optimizer_context_replay::infuse_table_stats(TABLE *table)
return; // OOM
ulonglong *frequencies=
(ulonglong *) thd->alloc(sizeof(ulonglong) * num_key_parts);
(ulonglong *) thd->calloc(sizeof(ulonglong) * num_key_parts);
if (unlikely(!frequencies))
return; // OOM