Re: [GENERAL] Security implications of (plpgsql) functions

[ Thread moved to hackers.]

Crash reproduced here.

My guess is that you are recursing and crashing the backend, which then
forces the other backends to reset. I think we need to fix this by
either setting a limit in the amount of function recursion, or allowing
only the offending backend to crash without forcing all the other
backends to crash.

---------------------------------------------------------------------------

Marcin Owsiany wrote:
> CREATE FUNCTION "x" (integer) RETURNS integer AS '
> BEGIN
>     RETURN x(0);
> END' LANGUAGE 'plpgsql' WITH ( isstrict );
> SELECT x(0);
> server closed the connection unexpectedly
>         This probably means the server terminated abnormally
>         before or while processing the request.
> The connection to the server was lost. Attempting reset: Failed.
> !>
> 
> The log says:
>  DEBUG:  server process (pid 3550) was terminated by signal 11
>  DEBUG:  terminating any other active server processes
> 
> The thing that worries me most is the last message: postmaster terminates all
> other backends, therefore overflowing the stack via a plpgsql function can be
> used to DoS-attack the server.
> 
> Is there anything one (as a postgresql installation admin) can do?  Disabling
> procedural languages in databases of the users I don't trust comes to mind, but
> does it really make me safe? I mean: won't such attack still be possible with
> pure SQL?
> 
> regards,
> 
> Marcin
> -- 
> Marcin Owsiany <marcin@owsiany.pl>              http://marcin.owsiany.pl/
> GnuPG: 1024D/60F41216  FE67 DA2D 0ACA FC5E 3F75  D6F6 3A0D 8AA0 60F4 1216
>  
> "Every program in development at MIT expands until it can read mail."
>                                                               -- Unknown
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