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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Amul Sul <sulamul@gmail.com>
Cc: Sravan Kumar <sravanvcybage@gmail.com>
Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: pg_verifybackup: TAR format backup verification
Date: Mon, 30 Sep 2024 11:31:01 -0400
Message-ID: <1467228.1727710261@sss.pgh.pa.us> (raw)
In-Reply-To: <CA+TgmobHgpOnRSxJbWTVn9ZZ9SmoXxXw4-_R_ycEvOdJqKH0WA@mail.gmail.com>
References: <CAAJ_b94StvLWrc_p4q-f7n3OPfr6GhL8_XuAg2aAaYZp1tF-nw@mail.gmail.com>
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Robert Haas <robertmhaas@gmail.com> writes:
> On Sun, Sep 29, 2024 at 1:03 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>>> CID 1620458:  Resource leaks  (RESOURCE_LEAK)
>>> Variable "buffer" going out of scope leaks the storage it points to.

> This looks like a real leak. It can only happen once per tarfile when
> verifying a tar backup so it can never add up to much, but it makes
> sense to fix it.

+1

>>> CID 1620457:  Memory - illegal accesses  (OVERRUN)
>>> Overrunning array of 296 bytes at byte offset 296 by dereferencing pointer "(char *)&mystreamer->control_file + mystreamer->control_file_bytes".

> I think this might be complaining about a potential zero-length copy.
> Seems like perhaps the <= sizeof(ControlFileData) test should actually
> be < sizeof(ControlFileData).

That's clearly an improvement, but I was wondering if we should also
change "len" and "remaining" to be unsigned (probably size_t).
Coverity might be unhappy about the off-the-end array reference,
but perhaps it's also concerned about what happens if len is negative.

>>> CID 1620456:  Null pointer dereferences  (FORWARD_NULL)
>>> Passing null pointer "suffix" to "strcmp", which dereferences it.

> This one is happening, I believe, because report_backup_error()
> doesn't perform a non-local exit, but we have a bit of code here that
> acts like it does.

Check.

> Patch attached.

WFM, modulo the suggestion about changing data types.

			regards, tom lane





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  Cc: tgl@sss.pgh.pa.us, robertmhaas@gmail.com, sulamul@gmail.com, sravanvcybage@gmail.com
  Subject: Re: pg_verifybackup: TAR format backup verification
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