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Re: [libvirt] [PATCH 1/2] storage: Resolve storage driver crash



On Mon, Nov 06, 2017 at 03:53:08PM -0500, John Ferlan wrote:
Resolve a storage driver crash as a result of a long running
storageVolCreateXML when the virStorageVolPoolRefreshThread is
run as a result of a storageVolUpload complete and ran the
virStoragePoolObjClearVols without checking if the creation
code was currently processing a buildVol after incrementing
the driver->asyncjob count.

I thought the whole point of refreshing the pool in a thread
was to have the storage driver usable for other things.
This effectively disables pool refresh during long-running
jobs.


The refreshThread needs to wait until all creation threads
are completed so as to not alter the volume list while the
volume is being built.

Crash from valgrind is as follows (with a bit of editing):

==21309== Invalid read of size 8
==21309==    at 0x153E47AF: storageBackendUpdateVolTargetInfo
==21309==    by 0x153E4C30: virStorageBackendUpdateVolInfo
==21309==    by 0x153E52DE: virStorageBackendVolRefreshLocal
==21309==    by 0x153DE29E: storageVolCreateXML

This is a fault of storageVolCreateXML for using invalid objects
after dropping the locks.

Jan

==21309==    by 0x562035B: virStorageVolCreateXML
==21309==    by 0x147366: remoteDispatchStorageVolCreateXML
...
==21309==  Address 0x2590a720 is 64 bytes inside a block of size 336 free'd
==21309==    at 0x4C2F2BB: free
==21309==    by 0x54CB9FA: virFree
==21309==    by 0x55BC800: virStorageVolDefFree
==21309==    by 0x55BF1D8: virStoragePoolObjClearVols
==21309==    by 0x153D967E: virStorageVolPoolRefreshThread
...
==21309==  Block was alloc'd at
==21309==    at 0x4C300A5: calloc
==21309==    by 0x54CB483: virAlloc
==21309==    by 0x55BDC1F: virStorageVolDefParseXML
==21309==    by 0x55BDC1F: virStorageVolDefParseNode
==21309==    by 0x55BE5A4: virStorageVolDefParse
==21309==    by 0x153DDFF1: storageVolCreateXML
==21309==    by 0x562035B: virStorageVolCreateXML
==21309==    by 0x147366: remoteDispatchStorageVolCreateXML
...

Signed-off-by: John Ferlan <jferlan redhat com>
---
src/storage/storage_driver.c | 9 +++++++++
1 file changed, 9 insertions(+)

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