Re: [PATCH] vhost-vdpa: free iommu domain after last use during cleanup

[Stefano Garzarella]

On Wed, Mar 01, 2023 at 10:02:01PM +0530, Gautam Dawar wrote:
> Currently vhost_vdpa_cleanup() unmaps the DMA mappings by calling
> `iommu_unmap(v->domain, map->start, map->size);`
> from vhost_vdpa_general_unmap() when the parent vDPA driver doesn't
> provide DMA config operations.
>
> However, the IOMMU domain referred to by `v->domain` is freed in
> vhost_vdpa_free_domain() before vhost_vdpa_cleanup() in
> vhost_vdpa_release() which results in NULL pointer de-reference.
> Accordingly, moving the call to vhost_vdpa_free_domain() in
> vhost_vdpa_cleanup() would makes sense. This will also help
> detaching the dma device in error handling of vhost_vdpa_alloc_domain().

Yep, good cleanup!

> This issue was observed on terminating QEMU with SIGQUIT.
>
> Fixes: 037d4305569a ("vhost-vdpa: call vhost_vdpa_cleanup during the release")
> Signed-off-by: Gautam Dawar <gautam.dawar@xxxxxxx>
> ---
> drivers/vhost/vdpa.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)

Reviewed-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>