On Mon, Feb 12, 2018 at 11:52:43AM +0100, Michal Privoznik wrote:
On 02/12/2018 11:08 AM, Daniel P. Berrangé wrote:
The fix for CVE-2018-6764 introduced a potential deadlock scenario that gets triggered by the NSS module when virGetHostname() calls getaddrinfo to resolve the hostname:
#0 0x00007f6e714b57e7 in futex_wait #1 futex_wait_simple #2 __pthread_once_slow #3 0x00007f6e71d16e7d in virOnce #4 0x00007f6e71d0997c in virLogInitialize #5 0x00007f6e71d0a09a in virLogVMessage #6 0x00007f6e71d09ffd in virLogMessage #7 0x00007f6e71d0db22 in virObjectNew #8 0x00007f6e71d0dbf1 in virObjectLockableNew #9 0x00007f6e71d0d3e5 in virMacMapNew #10 0x00007f6e71cdc50a in findLease #11 0x00007f6e71cdcc56 in _nss_libvirt_gethostbyname4_r #12 0x00007f6e724631fc in gaih_inet #13 0x00007f6e72464697 in __GI_getaddrinfo #14 0x00007f6e71d19e81 in virGetHostnameImpl #15 0x00007f6e71d1a057 in virGetHostnameQuiet #16 0x00007f6e71d09936 in virLogOnceInit #17 0x00007f6e71d09952 in virLogOnce #18 0x00007f6e714b5829 in __pthread_once_slow #19 0x00007f6e71d16e7d in virOnce #20 0x00007f6e71d0997c in virLogInitialize #21 0x00007f6e71d0a09a in virLogVMessage #22 0x00007f6e71d09ffd in virLogMessage #23 0x00007f6e71d0db22 in virObjectNew #24 0x00007f6e71d0dbf1 in virObjectLockableNew #25 0x00007f6e71d0d3e5 in virMacMapNew #26 0x00007f6e71cdc50a in findLease #27 0x00007f6e71cdc839 in _nss_libvirt_gethostbyname3_r #28 0x00007f6e71cdc724 in _nss_libvirt_gethostbyname2_r #29 0x00007f6e7248f72f in __gethostbyname2_r #30 0x00007f6e7248f494 in gethostbyname2 #31 0x000056348c30c36d in hosts_keys #32 0x000056348c30b7d2 in main
Fortunately the extra stuff virGetHostname does is totally irrelevant to the needs of the logging code, so we can just inline a call to the native hostname() syscall directly.
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> --- src/util/virlog.c | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-)
ACK
FYI I'll also squash in a change to cfg.mk to avoid syntax-check failure diff --git a/cfg.mk b/cfg.mk index 78f805b27e..920b609172 100644 --- a/cfg.mk +++ b/cfg.mk @@ -1183,7 +1183,7 @@ _src2=src/(util/vircommand|libvirt|lxc/lxc_controller|locking/lock_daemon|loggin exclude_file_name_regexp--sc_prohibit_fork_wrappers = \ (^($(_src2)|tests/testutils|daemon/libvirtd)\.c$$) -exclude_file_name_regexp--sc_prohibit_gethostname = ^src/util/virutil\.c$$ +exclude_file_name_regexp--sc_prohibit_gethostname = ^src/util/vir(util|log)\.c$$ exclude_file_name_regexp--sc_prohibit_internal_functions = \ ^src/(util/(viralloc|virutil|virfile)\.[hc]|esx/esx_vi\.c)$$ Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|