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

[Alex Williamson <alex.williamson@redhat.com>]

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.

>          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);