Re: Underscore in positional parameters?

From: Erik Wienhold <ewie(at)ewie(dot)name>
To: Alexander Lakhin <exclusion(at)gmail(dot)com>
Cc: Michael Paquier <michael(at)paquier(dot)xyz>, Peter Eisentraut <peter(at)eisentraut(dot)org>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Underscore in positional parameters?
Date: 2024-05-19 14:43:39
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On 2024-05-19 07:00 +0200, Alexander Lakhin wrote:
> I encountered anomalies that you address with this patch too.
> And I can confirm that it fixes most cases, but there is another one:
> SELECT $300000000 \bind 'foo' \g
> ERROR:  invalid memory alloc request size 1200000000
> Maybe you would find this worth fixing as well.

Yes, that error message is not great. In variable_paramref_hook we
check paramno > INT_MAX/sizeof(Oid) when in fact MaxAllocSize/sizeof(Oid)
is the more appropriate limit to avoid that unspecific alloc size error.

Fixed in v4 with a separate patch because it's unrelated to the param
number parsing. But it fits nicely into the broader issue on the upper
limit for param numbers. Note that $268435455 is still the largest
possible param number ((2^30-1)/4) and that we just return a more
user-friendly error message for params beyond that limit.


Attachment Content-Type Size
v4-0001-Fix-overflow-in-parsing-of-positional-parameter.patch text/x-diff 2.8 KB
v4-0002-Limit-max-parameter-number-with-MaxAllocSize.patch text/x-diff 2.7 KB

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