bugs in spool_copy_message() (fwd)

[Alan Thew]

I found this mail (in my own cyrus archive) today after one of our users 
was getting messages rejected which they had sent locally. I get rid of 
NULLs during delivery (before it reaches Cyrus) and assumed it was a bug 
in delivery. In fact Cyrus (2.2.12) still produces:

554 5.6.0 Message contains NUL characters

when it sees a line longer than 8190 bytes.

I'm not objecting to a limit in line length but it would be useful if the 
error message was relevant.

Thanks

-- 
Alan Thew                                       alan.thew at liverpool.ac.uk
Computing Services, University of Liverpool     Fax: +44 151 794-4442

---------- Forwarded message ----------
Date: Wed, 27 Oct 2004 17:23:39 +0100 (GMT Daylight Time)
From: Philip Chambers <P.A.Chambers at exeter.ac.uk>
To: info-cyrus at lists.andrew.cmu.edu
Subject: bugs in spool_copy_message()

I have just found two flaws in the code which takes a message into cyrus (typically
during the DATA phase of LMTP.  I am amazed that one has existed for so long.

It means that messages with a line longer that 8190 bytes will be rejected with the
error "Message contains NUL characters".  (Confirmed in testing.)

The code is in spool_copy_message() in spool.c (used to be in copy_message() in
lmtpengine.c.

The problems are in the loop: while(prot_fgets(...)).

The code after "else if (p[0] == '\r')" ignores the case of a long line which
contains \r\0 within it when it is the \0 which fills the buffer.  The code will
fail to notice the \0.

More importantly, a line longer than 8190 characters will be picked up by the else
statement (else if (p[0] != '\n') and treated as if it has a \0 in it even though it
does not!

I am about to work out a fix but, given the importance of this code, I need to spend
a lot of time making sure I do not introduce a new bug.

As I said, I find it hard to believe that cyrus has been unable to handle long lines
for so long!

Phil.
---------------------------------------
Phil Chambers (postmaster at exeter.ac.uk)
University of Exeter

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