Re: [Qemu-devel] [PATCH] nvdimm acpi: fix g_array_free() with NULL pointer

[Xiao Guangrong <guangrong.xiao@linux.intel.com>]

CCed Haozhong

On 01/12/2017 07:09 PM, Stefan Hajnoczi wrote:
> On Thu, Jan 12, 2017 at 11:18:25AM +0800, Xiao Guangrong wrote:
>>
>>
>> On 01/11/2017 05:36 PM, Stefan Hajnoczi wrote:
>>> Unlike g_free(), g_array_free() does not accept a NULL pointer argument.
>>> The following error is logged when an nvdimm device is realized:
>>>
>>>   GLib-CRITICAL **: g_array_free: assertion 'array' failed
>>>
>>> Cc: Xiao Guangrong <guangrong.xiao@linux.intel.com>
>>> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
>>> ---
>>>  hw/acpi/nvdimm.c | 4 +++-
>>>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> NACK
>
>>>
>>> diff --git a/hw/acpi/nvdimm.c b/hw/acpi/nvdimm.c
>>> index 8e7d6ec..8f0a484 100644
>>> --- a/hw/acpi/nvdimm.c
>>> +++ b/hw/acpi/nvdimm.c
>>> @@ -375,7 +375,9 @@ static void nvdimm_init_fit_buffer(NvdimmFitBuffer *fit_buf)
>>>
>>>  static void nvdimm_build_fit_buffer(NvdimmFitBuffer *fit_buf)
>>>  {
>>> -    g_array_free(fit_buf->fit, true);
>>> +    if (fit_buf->fit) {
>>> +        g_array_free(fit_buf->fit, true);
>>> +    }
>>
>> Er, i do not know why it is NULL as we have init-ed it in nvdimm_init_fit_buffer:
>>
>> static void nvdimm_init_fit_buffer(NvdimmFitBuffer *fit_buf)
>> {
>>     fit_buf->fit = g_array_new(false, true /* clear */, 1);
>> }
>>
>> And i can not reproduce it on my box, could you share your command line and the
>> based commit id?
>
> Good point, it happens when nvdimm_plug() is called but -M pc,nvdimm is
> missing from the command-line.  This means nvdimm_init_acpi_state() was
> not called by pc_init1():
>
>   $ x86_64-softmmu/qemu-system-x86_64 \
>       -enable-kvm \
>       -m 1G,slots=2,maxmem=16G \
>       -drive if=virtio,file=test.img,format=raw \
>       -object memory-backend-file,id=hostmem0,mem-path=mydimm,share=on,size=8G \
>       -device nvdimm,id=nvdimm0,memdev=hostmem0
>
> Do you want to audit the code to check if anything else misbehaves when
> -device nvdimm is used without -M pc,nvdimm?

Yes. Haozhong will help me to audit the code and fix this crash.

Thanks for your report, Stefan!