#646005 popa3d chokes on files larger than 2GiB (it seems)

Package:
popa3d
Source:
popa3d
Description:
Tiny POP3 daemon, designed with security as the primary goal
Submitter:
Carlos Carvalho
Date:
2025-08-24 15:43:02 UTC
Severity:
normal
#646005#5
Date:
2011-10-20 14:25:48 UTC
From:
To:
In a 32bit machine one user cannot access his email through popa3d.
The message in the log is

Oct 19 09:24:31 hoggar popa3d[25622]: Authentication passed for <user>
Oct 19 09:24:31 hoggar popa3d[25622]: Failed or refused to load /var/mail/<user>

Access is fine for the other pop users. This user works fine with
imap. I suspect it's a file size problem, because his spool is a
little over 2GiB.

Is popa3d limited to 2GiB file sizes?
#646005#10
Date:
2011-10-20 14:51:23 UTC
From:
To:
Yes, from params.h

/*
  * Introduce some sane limits on the mailbox size in order to prevent
  * a single huge mailbox from stopping the entire POP service.
  *
  * The defaults are rather large (2 GB filled with messages as small as
  * 1 KB each).  It is recommended that you decrease MAX_MAILBOX_MESSAGES,
  * MAX_MAILBOX_OPEN_BYTES, and MAX_MAILBOX_WORK_BYTES to, say, 100000,
  * 100000000 (100 MB), and 150000000 (150 MB), respectively, if that
  * would be sufficient for your users.
  */
#define MAX_MAILBOX_MESSAGES            2097152
#define MAX_MAILBOX_OPEN_BYTES          2147483647
#define MAX_MAILBOX_WORK_BYTES          2147483647

   eloy
#646005#15
Date:
2025-08-24 15:40:27 UTC
From:
To:
So reported issue not a bug, just a defined limit.

It looks to me that the source code is *not* safe for 64-bit file
offsets in 32-bit archs. However, the limit above is a compile-time
limit and described by the author as extreme, recommending a shorter
maximum be applied downstream.

In practice mailboxes this size seem likely to be Maildir, not mbox, and
I understand that the upstream author would be considering applying the
Maildir patch in any new releases [1].

That said, it would be nice to fix as a code quality/resilience
improvement.

Shall we reclassify as wishlist?

[1] https://github.com/openwall/popa3d/pull/2#issuecomment-3203873730