Re: segfault errors on using numbers in execute statements

Sam Smith wrote:
> The below fragment of code either segfaults or gives the
> following error when run on OpenBSD 4.0-beta:
>     FREE ERROR BIND!FREE ERROR FBIND!

Probably your problem is the same of mine (using OpenBSD 3.9-stable amd64).

I just sent an email to "[email protected]". I quote it here too for 
convenience.

Bye.



-------- Original Message --------
Subject: Memory access problem with DBI or DBD-Mysql?
Date: Sat, 12 Aug 2006 14:25:03 +0200
From: Federico Giannici <[email protected]>
Organization: Neomedia srl
To: [email protected]

It seems to me that there is some kind of memory access problem with DBI
or DBD-Mysql.

I'm using OpenBSD 3.9-stable amd64. On OpenBSD 3.3 i386 the problem
didn't appeared. As you may know, recent version of OpenBSD have a new
kind of memory handling that make the programs segfault when they try to
access no (longer) allocated memory.

I'm using DBI 1.45 and DBD-Mysql 2.9008. I tried DBI 1.52 and DBD-Mysql
3.0006, but the problems were more frequent, so I remained to the old
versions.

Here is the problem: frequently some "do" commands cause perl to crash
with signal 11. The crashes seems to depend on a lot of factors. For
example, loading more libraries could make the program to start working.
I think it depends on the structure of the memory allocated to the program.

Here is the "bt" output of the core dump:

#0  0x000000005260a736 in mysql_st_internal_execute (h=0x4713b6e0,
statement=0x479b7140, attribs=0x4aa5fd40, numParams=0, params=0x0,
     cdaPtr=0x7f7ffffc8610, svsock=0x43c90498, use_mysql_use_result=0)
at dbdimp.c:1654
#1  0x0000000052612da3 in XS_DBD__mysql__db_do (cv=0x40970b20) at
mysql.xs:222
#2  0x0000000050ddf07b in XS_DBI_dispatch () from
/usr/local/libdata/perl5/site_perl/amd64-openbsd/auto/DBI/DBI.so
#3  0x000000004a5a1c47 in Perl_pp_entersub () at
/usr/src/gnu/usr.bin/perl/pp_hot.c:2890
#4  0x000000004a60899e in Perl_runops_standard () at
/usr/src/gnu/usr.bin/perl/run.c:37
#5  0x000000004a5f744d in S_run_body (oldscope=1) at
/usr/src/gnu/usr.bin/perl/perl.c:1936
#6  0x000000004a5f7231 in perl_run (my_perl=0x45356258) at
/usr/src/gnu/usr.bin/perl/perl.c:1855
#7  0x0000000000401afe in main ()

I have found the problem is caused by accessing
"imp_dbh->bind_type_guessing" for the call to ParseParam() inside
mysql_st_internal_execute().

I have verified that "imp_dbh" is NOT null, but trying to access any
member make the program segfault. So maybe the pointer is a stale one?

I have not enough knowledge of DBI to make more debugging.


Bye.


-- 
___________________________________________________
     __
    |-                      [email protected]
    |ederico Giannici      http://www.neomedia.it
___________________________________________________

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