[libvirt] [PATCH 3/3] virQEMUCapsSetHostModel: Free cpuData before setting it

[Michal Privoznik]

On 05/30/2018 06:57 PM, Peter Krempa wrote:
> On Wed, May 30, 2018 at 18:04:29 +0200, Michal Privoznik wrote:
>> While this leak happens in tests only, it is still worth fixing.
>>
>> ==12962== 2,035 (104 direct, 1,931 indirect) bytes in 1 blocks are definitely lost in loss record 325 of 331
>> ==12962==    at 0x4C2CF26: calloc (vg_replace_malloc.c:711)
>> ==12962==    by 0x5D285D5: virAlloc (viralloc.c:144)
>> ==12962==    by 0x5E823EB: virCPUGetHost (cpu.c:411)
>> ==12962==    by 0x56DE953: virQEMUCapsInitHostCPUModel (qemu_capabilities.c:2874)
>> ==12962==    by 0x56E062F: virQEMUCapsLoadCache (qemu_capabilities.c:3435)
>> ==12962==    by 0x13802F: qemuTestParseCapabilitiesArch (testutilsqemu.c:500)
>> ==12962==    by 0x1371F0: mymain (qemuxml2argvtest.c:2871)
>> ==12962==    by 0x13AD0B: virTestMain (testutils.c:1120)
>> ==12962==    by 0x1372FD: main (qemuxml2argvtest.c:2883)
>>
>> Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
>> ---
>>  src/qemu/qemu_capabilities.c | 4 ++++
>>  1 file changed, 4 insertions(+)
>>
>> diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
>> index e2e76e4dd8..9ec9089d5b 100644
>> --- a/src/qemu/qemu_capabilities.c
>> +++ b/src/qemu/qemu_capabilities.c
>> @@ -1857,6 +1857,10 @@ virQEMUCapsSetHostModel(virQEMUCapsPtr qemuCaps,
>>  {
>>      virQEMUCapsHostCPUDataPtr cpuData = virQEMUCapsGetHostCPUData(qemuCaps, type);
>>  
>> +    virCPUDefFree(cpuData->reported);
>> +    virCPUDefFree(cpuData->migratable);
>> +    virCPUDefFree(cpuData->full);
> 
> This looks fishy. The test code always unrefs the qemuCaps object, so
> there should be no leak. Could you please elaborate on how this happens?

Thing is, qemuTestParseCapabilitiesArch() calls virQEMUCapsLoadCache()
(which exists only for sake of tests) which does two things:

1) roughly in the middle it calls virQEMUCapsLoadHostCPUModelInfo()
where cpuData is firstly allocated

2) at the end it calls virQEMUCapsInitHostCPUModel() which overwrites
whatever was loaded in 1).

> 
> My problem is that this is in the setter code.
> 

Not at all. It's pretty common that setter frees whatever it is
replacing (e.g. virQEMUCapsSetGICCapabilities()).

Michal