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virtinst: Fix TOCTOU in pool and volume enumeration

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_fetch_all_pools_raw() and _fetch_vols_raw() have a race condition where
a pool/volume may disappear (from parallel libvirt operations) in
between enumerating and inspecting the objects.

_fetch_vols_raw() already expected that failure in the loop, but not for
the initial storagePoolLookupByName() call.

Also tighten the expected exception: This *should* crash on errors like
AttributeError or SystemExit, just not on dynamic libvirt errors. (Bare
exceptions are highly frowned upon in Python)

https://bugzilla.redhat.com/show_bug.cgi?id=1894359
This commit is contained in:
Martin Pitt 2020-11-05 13:38:15 +01:00 committed by Cole Robinson
parent 04ad8df752
commit 49a01b5482
1 changed files with 17 additions and 3 deletions
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20
virtinst/connection.py
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@ -192,7 +192,16 @@ class VirtinstConnection(object):
def _fetch_all_pools_raw(self):
dummy1, dummy2, ret = pollhelpers.fetch_pools(
self, {}, lambda obj, ignore: obj)
return [self._build_pool_raw(poolobj) for poolobj in ret]
pools = []
for poolobj in ret:
# TOCTOU race: a pool may go away in between enumeration and inspection
try:
pool = self._build_pool_raw(poolobj)
except libvirt.libvirtError as e: # pragma: no cover
log.debug("Fetching pool XML failed: %s", e)
continue
pools.append(pool)
return pools
def _fetch_all_nodedevs_raw(self):
dummy1, dummy2, ret = pollhelpers.fetch_nodedevs(
@ -202,7 +211,12 @@ class VirtinstConnection(object):
def _fetch_vols_raw(self, poolxmlobj):
ret = []
pool = self._libvirtconn.storagePoolLookupByName(poolxmlobj.name)
# TOCTOU race: a volume may go away in between enumeration and inspection
try:
pool = self._libvirtconn.storagePoolLookupByName(poolxmlobj.name)
except libvirt.libvirtError as e: # pragma: no cover
return ret
if pool.info()[0] != libvirt.VIR_STORAGE_POOL_RUNNING:
return ret
@ -213,7 +227,7 @@ class VirtinstConnection(object):
try:
xml = vol.XMLDesc(0)
ret.append(StorageVolume(weakref.proxy(self), parsexml=xml))
except Exception as e: # pragma: no cover
except libvirt.libvirtError as e: # pragma: no cover
log.debug("Fetching volume XML failed: %s", e)
return ret