[PATCH] viridentity: Fix ref/unref imbalance in VIR_IDENTITY_AUTORESTORE

[Daniel P. Berrangé]

On Mon, May 17, 2021 at 06:12:56PM +0200, Michal Privoznik wrote:
> The basic use case of VIR_IDENTITY_AUTORESTORE() is in
> conjunction with virIdentityElevateCurrent(). What happens is
> that virIdentityElevateCurrent() gets current identity (which
> increases the refcounter of thread local virIdentity object) and
> returns a pointer to it. Later, when the variable goes out of
> scope the virIdentityRestoreHelper() is called which calls
> virIdentitySetCurrent() over the old identity. But this means
> that the refcounter is increased again.
> 
> Therefore, we have to explicitly decrease the refcounter by
> calling g_object_unref().

Opps, yes, i remember thinking about this and clearly forgot
it again.

> 
> Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
> ---
> 
> I've observed this imbalance whilst running qemuxml2argvtest under
> valgrind:
> 
> ==10412== 949 (40 direct, 909 indirect) bytes in 1 blocks are definitely lost in loss record 524 of 539
> ==10412==    at 0x48397EF: malloc (vg_replace_malloc.c:307)
> ==10412==    by 0x50806F8: g_malloc (in /usr/lib64/libglib-2.0.so.0.6600.7)
> ==10412==    by 0x50992FD: g_slice_alloc (in /usr/lib64/libglib-2.0.so.0.6600.7)
> ==10412==    by 0x50999B9: g_slice_alloc0 (in /usr/lib64/libglib-2.0.so.0.6600.7)
> ==10412==    by 0x518D9AB: g_type_create_instance (in /usr/lib64/libgobject-2.0.so.0.6600.7)
> ==10412==    by 0x51739DC: g_object_new_internal (in /usr/lib64/libgobject-2.0.so.0.6600.7)
> ==10412==    by 0x5174F5C: g_object_new_with_properties (in /usr/lib64/libgobject-2.0.so.0.6600.7)
> ==10412==    by 0x5175978: g_object_new (in /usr/lib64/libgobject-2.0.so.0.6600.7)
> ==10412==    by 0x496C3C6: virIdentityNew (viridentity.c:407)
> ==10412==    by 0x496BF1A: virIdentityGetSystem (viridentity.c:318)
> ==10412==    by 0x117CEF: testCompareXMLToArgv (qemuxml2argvtest.c:653)
> ==10412==    by 0x148505: virTestRun (testutils.c:142)
> 
> Test #315 doesn't tickle the bug, while test #316 does.
> 
>  src/util/viridentity.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)

Reviewed-by: Daniel P. Berrangé <berrange at redhat.com>


Regards,
Daniel
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