Details
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Bug
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Status: Closed (View Workflow)
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Major
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Resolution: Fixed
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10.0.1
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None
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None
Description
Class Item_func_neg has a lot of conversions between signed and unsigned datatypes. I believe at least to some degree these conversions are undefined behavior in C++, and thus Item_func_neg can misbehave when compiled with optimizations. In particular I've experienced misbehavior in the main.func_math test on line 483. This line expects that negation of -9223372036854775808 will throw DATA_OUT_OF_RANGE error, but sometimes it doesn't. The following patch fixes the problem. Please consider including it (or some modification of it) into MariaDB.
--- a/sql/item_func.cc
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+++ b/sql/item_func.cc
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@@ -1908,6 +1908,8 @@ longlong Item_func_neg::int_op()
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if (args[0]->unsigned_flag &&
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(ulonglong) value > (ulonglong) LONGLONG_MAX + 1)
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return raise_integer_overflow();
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+ if (!args[0]->unsigned_flag && value == LONGLONG_MIN)
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+ return raise_integer_overflow();
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return check_integer_overflow(-value, !args[0]->unsigned_flag && value < 0);
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}
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Attachments
Activity
"This line expects that negation of -9223372036854775808 will throw DATA_OUT_OF_RANGE error, but sometimes it doesn't" .Pavel , can you please describe the environment necessary to reproduce this problem "sometimes does not"?
Here are my reproduction steps:
> clang --version
Ubuntu clang version 3.0-6ubuntu3 (tags/RELEASE_30/final) (based on LLVM 3.0)
Target: x86_64-pc-linux-gnu
Thread model: posix
> CC=clang CXX=clang++ cmake . DCMAKE_BUILD_TYPE=Release
...
> make
...
> cd mysql-test/
> ./mtr main.func_math
...
mysqltest: At line 483: query 'SELECT -a FROM t1' succeeded - should have failed with errno 1690...
...
Assigned to Wlad arbitrarily, just because I remember (possibly wrongly) him having an opinion on how to deal with longlong. Please reassign if needed.