Re: BUG #16837: Invalid memory access on \h in psql

At Tue, 26 Jan 2021 11:11:22 -0500, Tom Lane <tgl@sss.pgh.pa.us> wrote in 
> Kyotaro Horiguchi <horikyota.ntt@gmail.com> writes:
> > At Tue, 26 Jan 2021 07:00:00 +0000, PG Bug reporting form <noreply@postgresql.org> wrote in 
> >> When executing in psql (under valgrind):
> >> \h\
> >> valgrind detects the following error:
> >> ==00:00:00:00.000 3226182== 
> >> ==00:00:00:04.045 3226182== Conditional jump or move depends on
> >> uninitialised value(s)
> 
> > This is reproducible on master HEAD. helpSQL assumes that the first
> > word is longer than two characters and the second word exists. It also
> > doesn't care overruns. Addition to those issues, it miscounts the
> > length of the first two words if the third word exists.
> 
> Weirdly, valgrind isn't whining about this for me.  But I agree that
> that loop is unsafe.  There are other problems too I think: neither
> the initialization of "output" nor the calculation of nl_count seem
> to be done sanely.  This function really needs thoroughgoing review :-(

It looks far better now. Thanks!

regards.

-- 
Kyotaro Horiguchi
NTT Open Source Software Center