[libvirt] [PATCH v2] Fix Memory Leak in virQEMUCapsInitGuestFromBinary()

[Daniel P. Berrange]

On Thu, Mar 27, 2014 at 03:17:09AM +0530, Nehal J Wani wrote:
> While running qemucaps2xmltest, it was found that valgrind pointed out
> the following memory leaks:
> 
> ==29896== 0 bytes in 1 blocks are definitely lost in loss record 1 of 65
> ==29896==    at 0x4A0577B: calloc (vg_replace_malloc.c:593)
> ==29896==    by 0x4C6B45E: virAllocN (viralloc.c:191)
> ==29896==    by 0x4232A9: virQEMUCapsGetMachineTypesCaps (qemu_capabilities.c:1999)
> ==29896==    by 0x4234E7: virQEMUCapsInitGuestFromBinary (qemu_capabilities.c:789)
> ==29896==    by 0x41F10B: testQemuCapsXML (qemucaps2xmltest.c:118)
> ==29896==    by 0x41FFD1: virtTestRun (testutils.c:201)
> ==29896==    by 0x41EE7A: mymain (qemucaps2xmltest.c:203)
> ==29896==    by 0x42074D: virtTestMain (testutils.c:789)
> ==29896==    by 0x3E6CE1ED1C: (below main) (libc-start.c:226)
> ==29896== 
> ==29896== 0 bytes in 1 blocks are definitely lost in loss record 2 of 65
> ==29896==    at 0x4A0577B: calloc (vg_replace_malloc.c:593)
> ==29896==    by 0x4C6B45E: virAllocN (viralloc.c:191)
> ==29896==    by 0x4232A9: virQEMUCapsGetMachineTypesCaps (qemu_capabilities.c:1999)
> ==29896==    by 0x4234E7: virQEMUCapsInitGuestFromBinary (qemu_capabilities.c:789)
> ==29896==    by 0x41F10B: testQemuCapsXML (qemucaps2xmltest.c:118)
> ==29896==    by 0x41FFD1: virtTestRun (testutils.c:201)
> ==29896==    by 0x41EEA3: mymain (qemucaps2xmltest.c:204)
> ==29896==    by 0x42074D: virtTestMain (testutils.c:789)
> ==29896==    by 0x3E6CE1ED1C: (below main) (libc-start.c:226)
> 
> ---
>  src/qemu/qemu_capabilities.c |    4 ++++
>  1 files changed, 4 insertions(+), 0 deletions(-)
> 
> diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
> index 7673592..aef8bc1 100644
> --- a/src/qemu/qemu_capabilities.c
> +++ b/src/qemu/qemu_capabilities.c
> @@ -789,6 +789,10 @@ virQEMUCapsInitGuestFromBinary(virCapsPtr caps,
>      if (virQEMUCapsGetMachineTypesCaps(qemubinCaps, &nmachines, &machines) < 0)
>          goto cleanup;
>  
> +    /* Free unneeded memory given by malloc(0) */
> +    if (!nmachines)
> +        VIR_FREE(machines);
> +
>      /* We register kvm as the base emulator too, since we can
>       * just give -no-kvm to disable acceleration if required */
>      if ((guest = virCapabilitiesAddGuest(caps,

This doesn't look at all right either.  If nmachines is 0, then machines
should already be NULL.

Regards,
Daniel
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