On 2020-06-16 20:32 +0200, Alexander Strasser wrote:
On 2020-06-16 12:37 -0000, Stuart Henderson wrote:
On 2020-06-15, Alexander Strasser <eclipse7@gmx.net> wrote:
I had some imap crashes (sig11) starting at the end of 2019 after an upgrade of dovecot.
I found out, that I didn't have any problems using version v2.3.8, but any version v2.3.9 and higher would trigger the crashes.
After investigating more deeply and creating a core dump, I saw that the crash happened in an external plugin fetchmail_wakeup[1].
After recompiling that plugin with up to date dovecot headers, I didn't get crashes anymore.
So I suspect there were ABI incompatible changes and it was forgotten to bump the minimum Plugin-ABI version supported.
dovecot-2.3.8/configure #define DOVECOT_ABI_VERSION "2.3.ABIv8($PACKAGE_VERSION)"
dovecot-2.3.9/configure #define DOVECOT_ABI_VERSION "2.3.ABIv9($PACKAGE_VERSION)"
Did you disable version checking? (version_ignore = yes)
Thanks for the hint.
I couldn't find version_ignore anywhere in the configs. I also don't remember having changed it.
It's interesting that the ABI check didn't snap.
If I'm on the right track and the code src/lib/module-dir.c is responsible for loading plugins and doing the ABI check, then I think it does only check ABI compat for modules that define a symbol named <module-name>_version .
At first this looks a bit unsafe to me.
Though it explains why in my case there was no ABI check failing, as I found out the plugin does not define a version symbol.
The implementation should be really trivial, so I guess I will add it to the plugin.
I find the behaviour a bit surprising, but as I understand now, it's the plugin's fault and not a missed ABI bump in dovecot as I initially suspected.
Thanks for pointing me in the right direction.
Alexander