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1756d087cd
"set optimizer_switch to e or d causes invalid memory writes/valgrind warnings":
due to prefix support, the argument "e" was overwritten with its full value
"engine_condition_pushdown", which caused a buffer overrun.
This was wrong usage of find_type(); other wrong usages are fixed here too.
Please start reading with the comment of typelib.c.
client/mysqldump.c:
A bug: find_type() expects a bitmap as 3rd argument
(each bit is a flag controlling a behaviour of the function);
here it was instead passed the length of the string to search!
That could give random behaviour of find_type()
depending on the string.
We rather need to pass a correct flag to find_type().
The correct flag is FIND_TYPE_BASIC (0).
Flag 8 is not needed as buff cannot have a comma (see how buff is filled).
Flag 1 looks like a superfluous restriction.
Flag 4 is not user-friendly (why use
--compatible=2 rather than --compatible=mysql40 ?, and
we probably not commit to "2" always meaning "mysql40"
until the end of times).
include/mysql.h.pp:
This isn't a problematic API change as we go from char* to const char*:
existing code will run unchanged.
include/typelib.h:
named constants. Not an enum to not significantly change
the declaration of find_type() which would be an API change
(typelib.h is included in mysql.h).
mysql-test/r/mysqldump.result:
correct result (see the two requested modes in SQL_MODE)
mysql-test/suite/sys_vars/t/optimizer_switch_basic.test:
test for BUG#59894. The second SET used to crash.
mysql-test/t/mysqldump.test:
we had no test for multiple modes in --compatible, which is
supported according to --help
mysys/typelib.c:
Fix for BUG#59894. parse_name() is asked to match "e" with a row
of the TYPELIB (the TYPELIB lists permitted flags of optimizer_switch;
and comes from optimizer_switch_names[] of sys_vars.cc).
find_type() is capable of supporting prefixes, but if it is not
passed flag 2 in third argument, it will overwrite its first
argument (the string to search for) with the complete name,
here overwriting "e" with "engine_condition_pushdown". But
as this "e" was a buffer allocated in an Item, it was not big
enough to host the longer name, thus the crash.
We don't need to know the complete flag's name; the output used
from find_type() is just the flag's number (== function's return
code). So we can pass flag 2 to find_type() in parse_name().
After doing this fix and the other fixes in this patch, all usages
of find_type() were using flag 2; in most usages the string to search for,
is not guaranteed to be long enough to host the complete name
(it is either directly from argv, or from alloc_root/my_malloc
done in an earlier call).
Thus, flag 2 is here made implicit: callers need not pass it anymore,
it is always automatically turned on.
This allows to eliminate an oddity: parse_name() took a const char**,
and then removed "const" before calling find_type(), which could
theoretically modify the pointed data, thus lying on constness.
Last, constants for find_type() are now named.
sql-common/client.c:
Two bugs:
1) The enum was not in sync with the array (due to a bad porting of WL 1054;
the extra OPT_ values are about options present in 5.1 and deleted in 5.5);
added a compile_time_assert() to make sure this doesn't happen again
2) find_type() was writing past the end of opt_arg; as opt_arg was allocated
with alloc_root() with no extra space, this was an overrun; it could be seen
when
** building with -DWITH_VALGRIND -DHAVE_purify -DEXTRA_DEBUG
** making execution go through the faulty code; this faulty
code is executed only if the client asks to read a configuration
file like this:
mysql_options(mysql, MYSQL_READ_DEFAULT_FILE, "/tmp/cnf.cnf");
so by adding such line to the start of mysql_client_test.c::client_connect(),
we could see the valgrind warning:
==30548== Invalid write of size 1
==30548== at 0x4C2624C: strcpy (mc_replace_strmem.c:303)
==30548== by 0x48DC29: find_type (typelib.c:120)
==30548== by 0x465686: mysql_read_default_options (client.c:1344)
==30548== by 0x46830F: mysql_real_connect (client.c:2971)
==30548== by 0x409339: client_connect (mysql_client_test.c:331)
==30548== by 0x463A7F: main (mysql_client_test.c:19902)
==30548== Address 0x61875ad is 0 bytes after a block of size 29 alloc'd
==30548== at 0x4C25153: malloc (vg_replace_malloc.c:195)
==30548== by 0x49BFF1: my_malloc (my_malloc.c:38)
==30548== by 0x49C65C: alloc_root (my_alloc.c:166)
==30548== by 0x48EF97: handle_default_option (default.c:381)
==30548== by 0x49068C: search_default_file_with_ext (default.c:992)
==30548== by 0x48F929: search_default_file (default.c:670)
==30548== by 0x48EDC4: my_search_option_files (default.c:312)
==30548== by 0x48F4B1: my_load_defaults (default.c:576)
==30548== by 0x46517A: mysql_read_default_options (client.c:1207)
==30548== by 0x46830F: mysql_real_connect (client.c:2971)
==30548== by 0x409339: client_connect (mysql_client_test.c:331)
==30548== by 0x463A7F: main (mysql_client_test.c:19902)
This is fixed by having find_type() not overwrite anymore.
sql/sql_help.cc:
cast not needed anymore.
sql/table.cc:
cast not needed anymore.
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73 lines
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SET @start_global_value = @@global.optimizer_switch;
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SELECT @start_global_value;
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@start_global_value
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index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,engine_condition_pushdown=on
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select @@global.optimizer_switch;
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@@global.optimizer_switch
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index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,engine_condition_pushdown=on
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select @@session.optimizer_switch;
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@@session.optimizer_switch
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index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,engine_condition_pushdown=on
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show global variables like 'optimizer_switch';
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Variable_name Value
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optimizer_switch index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,engine_condition_pushdown=on
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show session variables like 'optimizer_switch';
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Variable_name Value
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optimizer_switch index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,engine_condition_pushdown=on
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select * from information_schema.global_variables where variable_name='optimizer_switch';
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VARIABLE_NAME VARIABLE_VALUE
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OPTIMIZER_SWITCH index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,engine_condition_pushdown=on
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select * from information_schema.session_variables where variable_name='optimizer_switch';
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VARIABLE_NAME VARIABLE_VALUE
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OPTIMIZER_SWITCH index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,engine_condition_pushdown=on
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set global optimizer_switch=10;
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set session optimizer_switch=5;
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select @@global.optimizer_switch;
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@@global.optimizer_switch
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index_merge=off,index_merge_union=on,index_merge_sort_union=off,index_merge_intersection=on,engine_condition_pushdown=off
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select @@session.optimizer_switch;
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@@session.optimizer_switch
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index_merge=on,index_merge_union=off,index_merge_sort_union=on,index_merge_intersection=off,engine_condition_pushdown=off
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set global optimizer_switch="index_merge_sort_union=on";
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set session optimizer_switch="index_merge=off";
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select @@global.optimizer_switch;
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@@global.optimizer_switch
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index_merge=off,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,engine_condition_pushdown=off
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select @@session.optimizer_switch;
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@@session.optimizer_switch
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index_merge=off,index_merge_union=off,index_merge_sort_union=on,index_merge_intersection=off,engine_condition_pushdown=off
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show global variables like 'optimizer_switch';
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Variable_name Value
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optimizer_switch index_merge=off,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,engine_condition_pushdown=off
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show session variables like 'optimizer_switch';
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Variable_name Value
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optimizer_switch index_merge=off,index_merge_union=off,index_merge_sort_union=on,index_merge_intersection=off,engine_condition_pushdown=off
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select * from information_schema.global_variables where variable_name='optimizer_switch';
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VARIABLE_NAME VARIABLE_VALUE
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OPTIMIZER_SWITCH index_merge=off,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,engine_condition_pushdown=off
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select * from information_schema.session_variables where variable_name='optimizer_switch';
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VARIABLE_NAME VARIABLE_VALUE
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OPTIMIZER_SWITCH index_merge=off,index_merge_union=off,index_merge_sort_union=on,index_merge_intersection=off,engine_condition_pushdown=off
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set session optimizer_switch="default";
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select @@session.optimizer_switch;
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@@session.optimizer_switch
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index_merge=off,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,engine_condition_pushdown=off
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set global optimizer_switch=1.1;
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ERROR 42000: Incorrect argument type to variable 'optimizer_switch'
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set global optimizer_switch=1e1;
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ERROR 42000: Incorrect argument type to variable 'optimizer_switch'
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set session optimizer_switch="index_merge";
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ERROR 42000: Variable 'optimizer_switch' can't be set to the value of 'index_merge'
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set session optimizer_switch="foobar";
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ERROR 42000: Variable 'optimizer_switch' can't be set to the value of 'foobar'
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#
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# Bug#59894 set optimizer_switch to e or d causes invalid
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# memory writes/valgrind warnings
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set global optimizer_switch = 'd';
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set global optimizer_switch = 'e';
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ERROR 42000: Variable 'optimizer_switch' can't be set to the value of 'e'
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SET @@global.optimizer_switch = @start_global_value;
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SELECT @@global.optimizer_switch;
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@@global.optimizer_switch
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index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,engine_condition_pushdown=on
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