From: Alexander Lakhin <exclusion@gmail.com>
To: Richard Guo <guofenglinux@gmail.com>
To: pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #17858: ExecEvalArrayExpr() leaves uninitialised memory for multidim array with nulls
Date: Tue, 21 Mar 2023 16:00:00 +0300
Message-ID: <4240d86f-7e9f-388b-fd96-f8944860c0f5@gmail.com> (raw)
In-Reply-To: <CAMbWs48CyDghUckGQbkbAB6uPdfzYS4X4Zkdfooausr5vaV9Bg@mail.gmail.com>
References: <17858-8fd287fd3663d051@postgresql.org>
<CAMbWs48CyDghUckGQbkbAB6uPdfzYS4X4Zkdfooausr5vaV9Bg@mail.gmail.com>
Hi Richard,
21.03.2023 14:52, Richard Guo wrote:
> Nice catch. This can also be seen on master.
>
> I searched the codes a little bit and found that in array_set_slice()
> and array_set_element() the 'newarray' is allocated with palloc0 and
> then the nulls bitmap is zeroed with
>
> MemSet(nullbitmap, 0, (nitems + 7) / 8);
>
> if havenulls is true. I wonder if we can do the same here.
I'm afraid that zeroing only bytes behind nitems bits is not enough, as outDatum() doesn't bother to calculate the exact
size of nulls bitmap, it just outputs all bytes of a datum (40 bytes in that case):
length = datumGetSize(value, typbyval, typlen);
...
for (i = 0; i < length; i++)
appendStringInfo(str, "%d ", (int) (s[i]));
Best regards,
Alexander
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Subject: Re: BUG #17858: ExecEvalArrayExpr() leaves uninitialised memory for multidim array with nulls
In-Reply-To: <4240d86f-7e9f-388b-fd96-f8944860c0f5@gmail.com>
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