Re: Underscore in positional parameters?

Peter Eisentraut <peter@eisentraut.org>

From: Peter Eisentraut <peter@eisentraut.org>
To: Erik Wienhold <ewie@ewie.name>, Alexander Lakhin <exclusion@gmail.com>
Cc: Michael Paquier <michael@paquier.xyz>, Tom Lane <tgl@sss.pgh.pa.us>, Dean Rasheed <dean.a.rasheed@gmail.com>, pgsql-hackers@postgresql.org
Date: 2024-07-02T08:14:23Z
Lists: pgsql-hackers
On 19.05.24 16:43, Erik Wienhold wrote:
> 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.

I have committed your two v4 patches.

I made a small adjustment in 0001: I changed the ecpg part to also store 
the result from strtoint() into a local variable before checking for 
error, like you had done in the scan.l part.  I think this is a bit 
better style.  In 0002 you had a typo in the commit message: MAX_INT 
instead of INT_MAX.




Commits

  1. Fix overflow in parsing of positional parameter

  2. Limit max parameter number with MaxAllocSize

  3. Re-forbid underscore in positional parameters