Re: BUG #17839: Heap-buffer overflow on float8_to_char with invalid template

Got it, I thought that since we were filling the string with #s there, we
should reposition the zero_end.

I will wait for your patch then, thanks for looking into it!

Cheers,

On Wed, Mar 15, 2023 at 12:45 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:

> Thiago Nunes <thiagotnunes@gmail.com> writes:
> > I think your solution deals with all the cases, but I would like to point
> > out how I fixed it locally. I recalculated Num.zero_end after this line (
> >
> https://github.com/postgres/postgres/blob/REL_15_2/src/backend/utils/adt/formatting.c#L6716
> > ):
>
> > ```
> > Num.zero_end = Num.pre + Num.post;
> > ```
>
> Hmm ... that seems a bit ad-hoc, because as far as I understand this
> code, zero_end is supposed to track where is the last '0' format
> character.  That shouldn't change just because we decided that the
> data value overflowed.
>
>                         regards, tom lane
>