Thread: [PATCH] FIx resource leaks (pg_resetwal.c)

Hi,

On 2020-04-23 15:20:59 -0300, Ranier Vilela wrote:
> Per Coverity.
> 
> read_controlfile alloc memory with pg_malloc and fail in releasing the
> memory.

Seriously, this is getting really ridiculous. You're posting badly
vetted, often nearly verbatim, coverity reports. Many of them are
obvious false positives. This is just producing noise.

Please stop.


> diff --git a/src/bin/pg_resetwal/pg_resetwal.c b/src/bin/pg_resetwal/pg_resetwal.c
> index 233441837f..673ab0204c 100644
> --- a/src/bin/pg_resetwal/pg_resetwal.c
> +++ b/src/bin/pg_resetwal/pg_resetwal.c
> @@ -608,6 +608,7 @@ read_controlfile(void)
>      len = read(fd, buffer, PG_CONTROL_FILE_SIZE);
>      if (len < 0)
>      {
> +        pg_free(buffer);        
>          pg_log_error("could not read file \"%s\": %m", XLOG_CONTROL_FILE);
>          exit(1);
>      }

There's an exit() two lines later, this is obviously not necessary.

Greetings,

Andres Freund

On Thu, Apr 23, 2020 at 11:41 AM Ranier Vilela <ranier.vf@gmail.com> wrote:
> And if I already propose a solution even if it is not the best, it is much better than being silent and missing the
opportunityto fix a bug.
 

The problem with that theory is that you're not creating any value
over simply running Coverity directly. Your patches don't seem to be
based on any real analysis beyond what makes Coverity stop
complaining, which is not helpful.

For example, the nbtree.c/btvacuumpage() issue you reported yesterday
involved a NULL pointer dereference, but if the code path in question
ever dereferenced the NULL pointer then it would be fundamentally
wrong in many other ways, probably leading to data corruption. The fix
that you posted obviously completely missed the point. Even when
Coverity identifies a serious issue, it usually needs to be carefully
interpreted.

Anybody can run Coverity. Many of us do. Maybe the approach you've
taken would have had a noticeable benefit if you were not dealing with
a codebase that has already been subject to lots of triage of Coverity
issues. But that's not the case.

> Ridiculous is your lack of education.

This isn't helping you at all.

--
Peter Geoghegan

On Thu, Apr 23, 2020 at 2:41 PM Ranier Vilela <ranier.vf@gmail.com> wrote:
> I do not agree in any way. At the very least what I am reporting is suspect. And if I already propose a solution even
ifit is not the best, it is much better than being silent and missing the opportunity to fix a bug.
 
> Ridiculous is your lack of education.

That's rather rude. I doubt that you know anything about how much
education Andres does nor does not have. The fact that he doesn't
agree with you does not mean that he is poorly educated.

On the substance of the issue, I see from the commit log that you've
gotten a few real issues fixed -- but I also agree with Andres that
you've reported a lot of things that are not real issues, and that
takes up other people's time looking at things that really don't
matter. Please make an effort not to report things that don't actually
need to be fixed.

pg_resetwal exits very quickly, generally in a small fraction of a
second. The allocation you're at pains to free only happens once per
execution and allocates only 8kB. Trying to free allocations that are
tiny and short-lived has no benefit. It's better to let the program
exit that much quicker, at which point all the memory is freed anyway.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company