Re: [RFC PATCH] hw/display/virtio-gpu: Fix memory leak (CID 1453811)

[Philippe Mathieu-Daudé]

If this is not a proper fix, what would be the correct one?

On 6/21/21 11:59 AM, Philippe Mathieu-Daudé wrote:
> ping?
> 
> On 6/14/21 12:52 PM, Philippe Mathieu-Daudé wrote:
>> ping?
>>
>> On 5/31/21 12:19 PM, Philippe Mathieu-Daudé wrote:
>>> To avoid leaking memory on the error path, reorder the
>>> code as:
>>> - check the parameters first
>>> - check resource already existing
>>> - finally allocate memory
>>>
>>> Reported-by: Coverity (CID 1453811: RESOURCE_LEAK)
>>> Fixes: e0933d91b1c ("virtio-gpu: Add virtio_gpu_resource_create_blob")
>>> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
>>> ---
>>> RFC because the s->iov check is dubious.
>>> ---
>>>  hw/display/virtio-gpu.c | 28 +++++++++++-----------------
>>>  1 file changed, 11 insertions(+), 17 deletions(-)
>>>
>>> diff --git a/hw/display/virtio-gpu.c b/hw/display/virtio-gpu.c
>>> index 4d549377cbc..8d047007bbb 100644
>>> --- a/hw/display/virtio-gpu.c
>>> +++ b/hw/display/virtio-gpu.c
>>> @@ -340,8 +340,15 @@ static void virtio_gpu_resource_create_blob(VirtIOGPU 
>>> *g,
>>>          return;
>>>      }
>>>  
>>> -    res = virtio_gpu_find_resource(g, cblob.resource_id);
>>> -    if (res) {
>>> +    if (cblob.blob_mem != VIRTIO_GPU_BLOB_MEM_GUEST &&
>>> +        cblob.blob_flags != VIRTIO_GPU_BLOB_FLAG_USE_SHAREABLE) {
>>> +        qemu_log_mask(LOG_GUEST_ERROR, "%s: invalid memory type\n",
>>> +                      __func__);
>>> +        cmd->error = VIRTIO_GPU_RESP_ERR_INVALID_PARAMETER;
>>> +        return;
>>> +    }
>>> +
>>> +    if (virtio_gpu_find_resource(g, cblob.resource_id)) {
>>>          qemu_log_mask(LOG_GUEST_ERROR, "%s: resource already exists %d\n",
>>>                        __func__, cblob.resource_id);
>>>          cmd->error = VIRTIO_GPU_RESP_ERR_INVALID_RESOURCE_ID;
>>> @@ -352,25 +359,12 @@ static void virtio_gpu_resource_create_blob(VirtIOGPU 
>>> *g,
>>>      res->resource_id = cblob.resource_id;
>>>      res->blob_size = cblob.size;
>>>  
>>> -    if (cblob.blob_mem != VIRTIO_GPU_BLOB_MEM_GUEST &&
>>> -        cblob.blob_flags != VIRTIO_GPU_BLOB_FLAG_USE_SHAREABLE) {
>>> -        qemu_log_mask(LOG_GUEST_ERROR, "%s: invalid memory type\n",
>>> -                      __func__);
>>> -        cmd->error = VIRTIO_GPU_RESP_ERR_INVALID_PARAMETER;
>>> -        g_free(res);
>>> -        return;
>>> -    }
>>> -
>>> -    if (res->iov) {
>>> -        cmd->error = VIRTIO_GPU_RESP_ERR_UNSPEC;
>>> -        return;
>>> -    }
>>> -
>>>      ret = virtio_gpu_create_mapping_iov(g, cblob.nr_entries, sizeof(cblob),
>>>                                          cmd, &res->addrs, &res->iov,
>>>                                          &res->iov_cnt);
>>> -    if (ret != 0) {
>>> +    if (ret != 0 || res->iov) {
>>>          cmd->error = VIRTIO_GPU_RESP_ERR_UNSPEC;
>>> +        g_free(res);
>>>          return;
>>>      }
>>>  
>>>
>>
>