Corrupted sizes in cache once again

[Aki Tuomi]

> On 02/02/2023 17:19 EET Stuart Henderson <stu at spacehopper.org> wrote:
> 
>  
> On 2023-02-01, Tim Evers <te-ml-ext at artfiles.de> wrote:
> > I run a fairly large Dovecot Installation (around 100k mailboxes) on 
> > several servers.
> >
> > gzip compression is on.
> >
> > Every once in a while I get the dreaded "cache corruption" messages in 
> > the log:
> >
> > Error: Corrupted record in index cache file 
> > /[redacted]/Maildir/dovecot.index.cache: UID 3868: Broken physical size 
> > in mailbox INBOX: 
> > read(zlib(/[redacted]/Maildir/cur/1674129792.M797543P21755.node2,S=8099,W=8276:2,)) 
> > failed: Cached message size smaller than expected (2877 < 8099, 
> > box=INBOX, UID=3868)
> >
> > Error: Corrupted record in index cache file 
> > /[redacted]/Maildir/dovecot.index.cache: UID 3875: Broken physical size 
> > in mailbox INBOX: 
> > read(zlib(/[redacted]/Maildir/cur/1674212201.M985809P29112.node2,S=13907,W=14121:2,)) 
> > failed: Cached message size smaller than expected (5533 < 8192, 
> > box=INBOX, UID=3875)
> >
> > The first entry shows 2877 (size on disk) vs. 8099 (real size unzipped, 
> > also in the filename: S=8099).
> >
> > The second entry shows 5533 (size on disk) vs. 8192 - this is not 
> > correct in any way. Size on disk is 13907 as noted in the filename.
> >
> > Both mails were delivered trough LMTP and retrieved by the POP3 service.
> >
> > Anyone with an idea what might be happening here? I've read all 
> > available info in the doc and in the previous discussions / bug reports, 
> > but nothing seems to match my case. And where does that 8192 come from - 
> > it looks suspicious?
> >
> > Version is 2.3.7.2 (Ubuntu 20.04)
> 
> 2.3.7.2 is rather old now. There were definitely fixes regarding compression
> around the 2.3.10-2.3.12 timeframe or thereabouts (I forget all the details
> but it took a release or two before some remaining issues were sorted out
> after changes in the area). I'd be looking to get it updated to a current
> version first.

For bug reports, we do ask that you try to reproduce it with 2.3.20 (current latest), you can get packages from https://repo.dovecot.org/ and would be nice if you can provide steps to reproduce this issue.

Also please see https://www.dovecot.org/bugreport-mail/ if you have not yet.

Aki