Re: LD_PRELOAD problem

  • From: "LS Cheng" <exriscer@xxxxxxxxx>
  • To: "Tanel Poder" <tanel.poder.003@xxxxxxx>
  • Date: Fri, 1 Sep 2006 14:13:25 +0200

Hi all

I have more information, I did a chatr to check differences between working
server oracle binary and the non working.

I see two differences, in the server which LD_PRELOAD doesnt cause problem
oracle binary has these two attributes:

explicit unloading disabled
linkage table protection disabled

Does anyone know how can I change these attributes with chatr?


On 8/31/06, Tanel Poder <tanel.poder.003@xxxxxxx> wrote:

LD_PRELOAD allows you to hijack dynamicly loaded library functions. If sqlplus calls function X, then if this function X is exported from your /sbl/ then this function X is called from /sbl/ even if it exists in some other dll against which the executable is linked (like libclntsh* libraries).

Run: nm /sbl/ to see which functions may be hijacked there, this
could give some more indication what's going on.

And of course, the library's word-size has to match word-size of the
executable. If the word sizes are different, you have to recompile the


*From:* oracle-l-bounce@xxxxxxxxxxxxx [mailto:
oracle-l-bounce@xxxxxxxxxxxxx] *On Behalf Of *LS Cheng
*Sent:* Thursday, August 31, 2006 04:45

*To:* Jesse, Rich
*Cc:* oracle-l
*Subject:* Re: LD_PRELOAD problem

However when I unset LD_PRELOAD sqlplus works but of course the
application specific program fails.

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