Description:
GCC 7 reports a warning/error here:
[ 47%] Building CXX object sql/CMakeFiles/sql.dir/sys_vars.cc.o
In file included from /usr/src/packages/BUILD/mysql-5.7.20/mysql-5.7.20/sql/sys_vars.cc:33:0:
/usr/src/packages/BUILD/mysql-5.7.20/mysql-5.7.20/sql/sys_vars.h: In member function ‘virtual bool Sys_var_gtid_mode::global_update(THD*, set_var*)’:
/usr/src/packages/BUILD/mysql-5.7.20/mysql-5.7.20/sql/sys_vars.h:2701:8: error: ‘' before you set @@GLOBAL.GTID_MODE = OFF.’ directive writing 42 bytes into a region of size between 5 and 389 [-Werror=format-overflow=]
bool global_update(THD *thd, set_var *var)
^~~~~~~~~~~~~
/usr/src/packages/BUILD/mysql-5.7.20/mysql-5.7.20/sql/sys_vars.h:2771:18: note: ‘sprintf’ output between 166 and 550 bytes into a destination of size 512
sprintf(buf, "replication channel '%.192s' is configured "
~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
"in AUTO_POSITION mode. Execute "
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
"CHANGE MASTER TO MASTER_AUTO_POSITION = 0 "
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
"FOR CHANNEL '%.192s' before you set "
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
"@@GLOBAL.GTID_MODE = OFF.",
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
mi->get_channel(), mi->get_channel());
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cc1plus: all warnings being treated as errors
This code may contain two bugs. First, the buffer is too small as GCC reports. Second, channel names can be up to 64 (Unicode) characters long. 192 in "%.192s" is 3*64. If the name contains only 4-byte names, then the name buffer must be 4*64+1 = 257 bytes long.
How to repeat:
Compile version 5.7.20 with GCC 7 and the following compile switches (only some of them are necessary to show the problem):
-m64 -fmessage-length=0 -fstack-protector -funwind-tables -fasynchronous-unwind-tables -Wno-implicit-fallthrough -Wno-int-in-bool-context -fPIC -Wall -Wextra -Wformat-security -Wvla -Woverloaded-virtual -Wno-unused-parameter -Werror -g -fabi-version=2 -fno-omit-frame-pointer -fno-strict-aliasing -std=gnu++03
Suggested fix:
Increate the buffer length.
Description: GCC 7 reports a warning/error here: [ 47%] Building CXX object sql/CMakeFiles/sql.dir/sys_vars.cc.o In file included from /usr/src/packages/BUILD/mysql-5.7.20/mysql-5.7.20/sql/sys_vars.cc:33:0: /usr/src/packages/BUILD/mysql-5.7.20/mysql-5.7.20/sql/sys_vars.h: In member function ‘virtual bool Sys_var_gtid_mode::global_update(THD*, set_var*)’: /usr/src/packages/BUILD/mysql-5.7.20/mysql-5.7.20/sql/sys_vars.h:2701:8: error: ‘' before you set @@GLOBAL.GTID_MODE = OFF.’ directive writing 42 bytes into a region of size between 5 and 389 [-Werror=format-overflow=] bool global_update(THD *thd, set_var *var) ^~~~~~~~~~~~~ /usr/src/packages/BUILD/mysql-5.7.20/mysql-5.7.20/sql/sys_vars.h:2771:18: note: ‘sprintf’ output between 166 and 550 bytes into a destination of size 512 sprintf(buf, "replication channel '%.192s' is configured " ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ "in AUTO_POSITION mode. Execute " ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ "CHANGE MASTER TO MASTER_AUTO_POSITION = 0 " ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ "FOR CHANNEL '%.192s' before you set " ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ "@@GLOBAL.GTID_MODE = OFF.", ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ mi->get_channel(), mi->get_channel()); ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ cc1plus: all warnings being treated as errors This code may contain two bugs. First, the buffer is too small as GCC reports. Second, channel names can be up to 64 (Unicode) characters long. 192 in "%.192s" is 3*64. If the name contains only 4-byte names, then the name buffer must be 4*64+1 = 257 bytes long. How to repeat: Compile version 5.7.20 with GCC 7 and the following compile switches (only some of them are necessary to show the problem): -m64 -fmessage-length=0 -fstack-protector -funwind-tables -fasynchronous-unwind-tables -Wno-implicit-fallthrough -Wno-int-in-bool-context -fPIC -Wall -Wextra -Wformat-security -Wvla -Woverloaded-virtual -Wno-unused-parameter -Werror -g -fabi-version=2 -fno-omit-frame-pointer -fno-strict-aliasing -std=gnu++03 Suggested fix: Increate the buffer length.