Description:
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ODBC (PDO) queries are causing segmentation error on 64 bit platforms under certain conditions if unixODBC is used to provide ODBC interface. The actual problem is definition of 'pdo_odbc_column' structure (in ext/pdo_odbc/php_pdo_odbc_int.h). The 'fetched_len' member is defined 'long'. However, in odbc_stmt.c (odbc_stmt_describe) the pointer on this member is passed as argument to SQLBindCol (ODBC library) which expects pointer on SQLINTEGER instead. On 64bit platforms unixODBC defines the 'SQLINTEGER' as 'int ' (a 32 bit number) and 'long' is a 64 bit number. 

On x86_64 this does not cause problems while negative numbers are not used. Therefore, the bug is rarely introduces itself. Unfortunately, in  the cases of NULL valued-columns it is possible  what '-1' is stored in this member variable. In this case the PhP while end up with segmentation fault.

I don't have access to formal ODBC specification and, therefore,don't really know if unixODBC correct in its implementation or violates specification. [ MS defines SQLINTEGER as 'long int'. But 'long int' on win64 is 32bit number. In Linux, 'long int' is 64bit and 'int' is 32bit ]. However, in either case the fix is very simple and will save php developers from lot headache. 

The proposed patch is available here:
http://dside.dyndns.org/projects/patches.dir/php-ds-odbc64.patch