Re: Invalid memory alloc request size for repeat()

On Wed, 25 May 2022 at 22:50, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Japin Li <japinli(at)hotmail(dot)com> writes:
>> Today, I try to use repeat() to generate 1GB text, and it occurs invalid memory
>> alloc request size [1]. It is a limit from palloc(), then I try to reduce it,
>> it still complains out of memory which comes from enlargeStringInfo() [2]. The
>> documentation about repect() [3] doesn't mentaion the limitation.
>
> It would probably make sense for repeat() to check this explicitly:
>
> if (unlikely(pg_mul_s32_overflow(count, slen, &tlen)) ||
> - unlikely(pg_add_s32_overflow(tlen, VARHDRSZ, &tlen)))
> + unlikely(pg_add_s32_overflow(tlen, VARHDRSZ, &tlen)) ||
> + unlikely(!AllocSizeIsValid(tlen)))
> ereport(ERROR,
> (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
> errmsg("requested length too large")));
>

LGTM. Thanks for your patch!

--
Regrads,
Japin Li.
ChengDu WenWu Information Technology Co.,Ltd.