From: Tom Lane <tgl@sss.pgh.pa.us>
To: Julien Rouhaud <rjuju123@gmail.com>
cc: wliang@stu.xidian.edu.cn, pgsql-bugs@lists.postgresql.org
Subject: Re: Report a potential bug caused by a improper call to pfree()
In-reply-to: <20220130133624.gmxsaxfvkbg4rz7y@jrouhaud>
References: <662c1e07.2b1.17ea8e13613.Coremail.wliang@stu.xidian.edu.cn>
 <20220130133624.gmxsaxfvkbg4rz7y@jrouhaud>
Comments: In-reply-to Julien Rouhaud <rjuju123@gmail.com>
	message dated "Sun, 30 Jan 2022 21:36:24 +0800"
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Date: Sun, 30 Jan 2022 10:29:27 -0500
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Julien Rouhaud <rjuju123@gmail.com> writes:
> On Sun, Jan 30, 2022 at 10:47:18AM +0800, wliang@stu.xidian.edu.cn wrote=
:
>> 1160                 /* Pop the stack */
>> 1161                 parent =3D stack->parent;
>> 1162                 pfree(stack);
>> =

>> I think it may be a potential bug and can be fixed without any side-eff=
ect as:
>> =

>> =

>> ++        if (stack !=3D &tail)
>> 1162                pfree(stack);

> I don't think it's necessary, it should be guaranteed that something as =
been
> pushed on the tail, ie. there shouldn't be a WJB_END_* before a correspo=
nding
> begin.

I've not checked the logic, but the lack of any reported crashes here
seems to confirm that there's no bug.

			regards, tom lane