Re: BUG #4680: Server crashed if using wrong (mismatch) conversion functions

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
Cc: Denis Afonin <vadm(at)itkm(dot)ru>, pgsql-bugs(at)postgresql(dot)org
Subject: Re: BUG #4680: Server crashed if using wrong (mismatch) conversion functions
Date: 2009-02-27 15:31:32
Message-ID: 18983.1235748692@sss.pgh.pa.us
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Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> writes:
> I think we should instead try to break the PANIC cycle. If we exceed
> ERRORDATA_STACK_SIZE, and we're already PANICing, we should just die
> immediately instead of throwing another PANIC about exceeding the stack
> size. The attached patch does that.

I don't think that's an improvement.

I'm not sure exactly why the previous fix for this type of problem
failed to cover this case --- did you identify why?

> However, a more serious issue is that a regular user can do that and
> bring down the whole system. I suggest that we make "CREATE [DEFAULT]
> CONVERSION" to call the conversion function with a empty string, to
> check that it is in fact capable of doing the conversion.

That part seems like a good idea, now that the conversion functions
throw errors (rather than Asserts) for wrong calls.

regards, tom lane

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