Details
Description
sql_mode='NO_UNSIGNED_SUBTRACTION' is supposed to allow the subtraction of two unsigned integers. However, in MariaDB it seems to allow only subtractions involving only ONE unsigned integer (if the result is negative).
SET SQL_MODE='NO_UNSIGNED_SUBTRACTION';
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SELECT CAST(0 AS UNSIGNED) - 1;
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+-------------------------+
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| CAST(0 AS UNSIGNED) - 1 |
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+-------------------------+
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| -1 |
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+-------------------------+
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SELECT 2-CAST(3 AS UNSIGNED);
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+-----------------------+
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| 2-CAST(3 AS UNSIGNED) |
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+-----------------------+
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| -1 |
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+-----------------------+
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SELECT CAST(1 AS UNSIGNED) - CAST(2 AS UNSIGNED);
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ERROR 1690 (22003): BIGINT value is out of range in 'cast(1 as unsigned) - cast(2 as unsigned)'
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This works in MySQL (tested version 5.6.40 and 8.0.39)
Error originally reported on https://mariadb.com/kb/en/scope-of-no_unsigned_subtraction/
Attachments
Issue Links
- relates to
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MDEV-30272 trigger sql_mode set to 'NO_UNSIGNED_SUBTRACTION' has no effect after upgrade from 10.3.37 to 10.4.27
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- Open
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Activity
caused by
commit 031f11717d9
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Author: Michael Widenius <monty@mariadb.org>
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Date: Sun Apr 18 15:29:13 2021 +0300
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Fix all warnings given by UBSAN
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The easiest way to compile and test the server with UBSAN is to run:
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./BUILD/compile-pentium64-ubsan
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and then run mysql-test-run.
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After this commit, one should be able to run this without any UBSAN
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warnings. There is still a few compiler warnings that should be fixed
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at some point, but these do not expose any real bugs.
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The 'special' cases where we disable, suppress or circumvent UBSAN are:
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- ref10 source (as here we intentionally do some shifts that UBSAN
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complains about.
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- x86 version of optimized int#korr() methods. UBSAN do not like unaligned
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memory access of integers. Fixed by using byte_order_generic.h when
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compiling with UBSAN
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- We use smaller thread stack with ASAN and UBSAN, which forced me to
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disable a few tests that prints the thread stack size.
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- Verifying class types does not work for shared libraries. I added
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suppression in mysql-test-run.pl for this case.
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- Added '#ifdef WITH_UBSAN' when using integer arithmetic where it is
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safe to have overflows (two cases, in item_func.cc).
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Things fixed:
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- Don't left shift signed values
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(byte_order_generic.h, mysqltest.c, item_sum.cc and many more)
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- Don't assign not non existing values to enum variables.
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- Ensure that bool and enum values are properly initialized in
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constructors. This was needed as UBSAN checks that these types has
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correct values when one copies an object.
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(gcalc_tools.h, ha_partition.cc, item_sum.cc, partition_element.h ...)
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- Ensure we do not called handler functions on unallocated objects or
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deleted objects.
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(events.cc, sql_acl.cc).
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- Fixed bugs in Item_sp::Item_sp() where we did not call constructor
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on Query_arena object.
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- Fixed several cast of objects to an incompatible class!
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(Item.cc, Item_buff.cc, item_timefunc.cc, opt_subselect.cc, sql_acl.cc,
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sql_select.cc ...)
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- Ensure we do not do integer arithmetic that causes over or underflows.
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This includes also ++ and -- of integers.
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(Item_func.cc, Item_strfunc.cc, item_timefunc.cc, sql_base.cc ...)
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- Added JSON_VALUE_UNITIALIZED to json_value_types and ensure that
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value_type is initialized to this instead of to -1, which is not a valid
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enum value for json_value_types.
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- Ensure we do not call memcpy() when second argument could be null.
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- Fixed that Item_func_str::make_empty_result() creates an empty string
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instead of a null string (safer as it ensures we do not do arithmetic
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on null strings).
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Other things:
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- Changed struct st_position to an OBJECT and added an initialization
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function to it to ensure that we do not copy or use uninitialized
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members. The change to a class was also motived that we used "struct
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st_position" and POSITION randomly trough the code which was
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confusing.
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- Notably big rewrite in sql_acl.cc to avoid using deleted objects.
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- Changed in sql_partition to use '^' instead of '-'. This is safe as
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the operator is either 0 or 0x8000000000000000ULL.
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- Added check for select_nr < INT_MAX in JOIN::build_explain() to
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avoid bug when get_select() could return NULL.
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- Reordered elements in POSITION for better alignment.
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- Changed sql_test.cc::print_plan() to use pointers instead of objects.
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- Fixed bug in find_set() where could could execute '1 << -1'.
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- Added variable have_sanitizer, used by mtr. (This variable was before
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only in 10.5 and up). It can now have one of two values:
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ASAN or UBSAN.
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- Moved ~Archive_share() from ha_archive.cc to ha_archive.h and marked
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it virtual. This was an effort to get UBSAN to work with loaded storage
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engines. I kept the change as the new place is better.
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- Added in CONNECT engine COLBLK::SetName(), to get around a wrong cast
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in tabutil.cpp.
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- Added HAVE_REPLICATION around usage of rgi_slave, to get embedded
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server to compile with UBSAN. (Patch from Marko).
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- Added #ifdef for powerpc64 to avoid a bug in old gcc versions related
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to integer arithmetic.
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Changes that should not be needed but had to be done to suppress warnings
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from UBSAN:
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- Added static_cast<<uint16_t>> around shift to get rid of a LOT of
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compiler warnings when using UBSAN.
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- Had to change some '/' of 2 base integers to shift to get rid of
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some compile time warnings.
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Reviewed by:
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- Json changes: Alexey Botchkov
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- Charset changes in ctype-uca.c: Alexander Barkov
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- InnoDB changes & Embedded server: Marko Mäkelä
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- sql_acl.cc changes: Vicențiu Ciorbaru
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- build_explain() changes: Sergey Petrunia
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This worked in MariaDB 10.3, stopped working in 10.4.