openSUSE 16.0
dovecot --version 2.4.5 (c2b286c37a)
For testing I do setenforce 0 (SELINUX permissive). I can access user data as expected (sudo -u dovesrv -g dovesrv ...).
I can see that imap-login is passed successfully. By doing IMAP manually, I can startup imap and catch the pid before it hangs with 99.9% cpu usage.
strace -tt -o log -p 38339
The log reads:
12:19:26.132613 epoll_wait(12, [{events=EPOLLIN, data=0x563fe74a18a0}], 8, 1783633) = 1 12:19:52.572739 read(9, "A005 LIST \"\" *\n", 8192) = 15 12:19:52.573009 write(7, "CATEGORY\tmailbox\tstorage\n", 25) = 25 12:19:52.573227 brk(0x563fe74ee000) = 0x563fe74ee000
Dovecot 2.4.4 worked as expected. Downgrading "fixes" the issue, however I feel that it is related to one of the CVEs.
Initially I suspected quota (but not acl, it ran through), because last debug messages are
dovecot: quota-status(user)<26312><SoNJOgYPr2rIZgAAluaoaw>: Debug: acl: initializing backend vfile dovecot: quota-status(user)<26312><SoNJOgYPr2rIZgAAluaoaw>: Debug: acl: acl username = florian dovecot: quota-status(user)<26312><SoNJOgYPr2rIZgAAluaoaw>: Debug: acl: owner = no dovecot: quota-status(user)<26312><SoNJOgYPr2rIZgAAluaoaw>: Debug: acl: ignore = no dovecot: quota-status(user)<26312><SoNJOgYPr2rIZgAAluaoaw>: Debug: quota-count: quota_over_status check: quota_over_mask unset - skipping dovecot: quota-status(user)<26312><SoNJOgYPr2rIZgAAluaoaw>: Debug: quota-count: quota_over_status check: quota_over_mask unset - skipping
Disabling quota-status service did not help though.
doveadm mailbox ... has the same effect.
Freeing cpu requires a kill -9 of imap, regular kill does not work.
Little wired is the package info, I guess packaging did not update the meta data. zypper info dovecot24 prints (see Version):
Repository : repo-oss (16.0) Name : dovecot24 Version : 2.4.4-160000.2.1 Arch : x86_64 Anbieter : SUSE LLC <https://www.suse.com/> Installierte Größe : 15,2 MiB Installiert : Ja Status : aktuell Quellpaket : dovecot24-2.4.4-160000.2.1.src Upstream-URL : https://www.dovecot.org Zusammenfassung : IMAP and POP3 Server Written Primarily with Security in Mind
-- Best Johannes Nohl