Re: [PATCH] vfio: Fix memory leak of hostwin

[Peng Liang <liangpeng10@huawei.com>]

On 11/17/2021 3:01 AM, Alex Williamson wrote:
> On Tue, 16 Nov 2021 19:56:26 +0800
> Peng Liang <liangpeng10@huawei.com> wrote:
> 
>> hostwin is allocated and added to hostwin_list in vfio_host_win_add, but
>> it is only deleted from hostwin_list in vfio_host_win_del, which causes
>> a memory leak.  Also, freeing all elements in hostwin_list is missing in
>> vfio_disconnect_container.
>>
>> Fix: 2e4109de8e58 ("vfio/spapr: Create DMA window dynamically (SPAPR IOMMU v2)")
>> CC: qemu-stable@nongnu.org
>> Signed-off-by: Peng Liang <liangpeng10@huawei.com>
>> ---
>>  hw/vfio/common.c | 12 ++++++++++--
>>  1 file changed, 10 insertions(+), 2 deletions(-)
>>
>> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
>> index dd387b0d3959..2cce60c5fac3 100644
>> --- a/hw/vfio/common.c
>> +++ b/hw/vfio/common.c
>> @@ -546,11 +546,12 @@ static void vfio_host_win_add(VFIOContainer *container,
>>  static int vfio_host_win_del(VFIOContainer *container, hwaddr min_iova,
>>                               hwaddr max_iova)
>>  {
>> -    VFIOHostDMAWindow *hostwin;
>> +    VFIOHostDMAWindow *hostwin, *next;
>>  
>> -    QLIST_FOREACH(hostwin, &container->hostwin_list, hostwin_next) {
>> +    QLIST_FOREACH_SAFE(hostwin, &container->hostwin_list, hostwin_next, next) {
> 
> Unnecessary conversion to _SAFE variant here, we don't continue to walk
> the list after removing an object.

Ok, I'll remove it in the next version.


Thanks,
Peng

> 
>>          if (hostwin->min_iova == min_iova && hostwin->max_iova == max_iova) {
>>              QLIST_REMOVE(hostwin, hostwin_next);
>> +            g_free(hostwin);
>>              return 0;
>>          }
>>      }
>> @@ -2239,6 +2240,7 @@ static void vfio_disconnect_container(VFIOGroup *group)
>>      if (QLIST_EMPTY(&container->group_list)) {
>>          VFIOAddressSpace *space = container->space;
>>          VFIOGuestIOMMU *giommu, *tmp;
>> +        VFIOHostDMAWindow *hostwin, *next;
>>  
>>          QLIST_REMOVE(container, next);
>>  
>> @@ -2249,6 +2251,12 @@ static void vfio_disconnect_container(VFIOGroup *group)
>>              g_free(giommu);
>>          }
>>  
>> +        QLIST_FOREACH_SAFE(hostwin, &container->hostwin_list, hostwin_next,
>> +                           next) {
>> +            QLIST_REMOVE(hostwin, hostwin_next);
>> +            g_free(hostwin);
>> +        }
>> +
> 
> This usage looks good.  Thanks,
> 
> Alex
> 
>>          trace_vfio_disconnect_container(container->fd);
>>          close(container->fd);
>>          g_free(container);
> 
> .
>