From: Gabor Gombas (no email)
Date: Thu Sep 13 2007 - 04:42:04 EDT
On Wed, Sep 12, 2007 at 08:10:29PM +0200, Alain Spineux wrote:
> When postfix try to deliver an email, it open a LMTP connection with cyrus
> and cyrus, instead of speaking correct LMTP reply with garbage.
> BUT 2aaaac388000-2aaaac479000 r-xp 00000000 fd:00 12452057 /lib64/libdb-4.3.so
> is not realy garbage this look like to be the memory areas of a process.
No, it's not garbage, it's part of the error message that glibc produces
when it encounters the error in the subject.
- Build Cyrus with full debugging info and no optimization (-g3 -O0)
- export CYRUS_VERBOSE=50
- Start Cyrus
- Send a message through postfix that is known to trigger the bug
- You've now 15 seconds to attach to the newly created lmtpd process with
gdb
- Let lmtpd continue until it crashes; post a full backtrace
Now, the bactrace will contain the location where the memory corruption
was _detected_, not where it had really occured, but that may still be
useful.
An other method would be to modify the "cmd=..." entry in cyrus.conf and
launch lmtpd inside valgrind. You still need to rebuild Cyrus with full
debugging info to get meaningful backtraces (use --num-callers=10 or
more), and it will be slow, but it has higher chance to catch the real
bug.
Gabor
--
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MTA SZTAKI Computer and Automation Research Institute
Hungarian Academy of Sciences
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