Re: [libvirt] [PATCH] log: fix deadlock obtaining hostname (related CVE-2018-6764)
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(a)redhat.com>
---
src/util/virlog.c | 20 ++++++++++++++------
1 file changed, 14 insertions(+), 6 deletions(-)
ACK
Michal