Hi On Tue, Mar 3, 2026 at 2:06 AM <[email protected]> wrote: > > From: Dongwon Kim <[email protected]> > > When a virtio-gpu resource is destroyed, any associated udmabuf must be > properly torn down. Currently, the code may leave dangling references > to dmabuf file descriptors in the scanout primary buffers. > > This patch updates virtio_gpu_fini_udmabuf to: > 1. Iterate through all active scanouts. > 2. Identify dmabufs that match the resource's file descriptor. > 3. Close the dmabuf and invalidate the resource's FD reference to > prevent use-after-free or double-close scenarios. > 4. Finally, trigger the underlying udmabuf destruction. > > This ensures that the display backend does not attempt to access > memory or FDs that have been released by the guest or the host. > > Cc: Gerd Hoffmann <[email protected]> > Cc: Marc-André Lureau <[email protected]> > Signed-off-by: Vivek Kasireddy <[email protected]> > Signed-off-by: Dongwon Kim <[email protected]>
Acked-by: Marc-André Lureau <[email protected]> > --- > include/hw/virtio/virtio-gpu.h | 3 ++- > hw/display/virtio-gpu-udmabuf.c | 25 ++++++++++++++++++------- > hw/display/virtio-gpu.c | 2 +- > 3 files changed, 21 insertions(+), 9 deletions(-) > > diff --git a/include/hw/virtio/virtio-gpu.h b/include/hw/virtio/virtio-gpu.h > index 58e0f91fda..65312f869d 100644 > --- a/include/hw/virtio/virtio-gpu.h > +++ b/include/hw/virtio/virtio-gpu.h > @@ -357,7 +357,8 @@ bool virtio_gpu_scanout_blob_to_fb(struct > virtio_gpu_framebuffer *fb, > /* virtio-gpu-udmabuf.c */ > bool virtio_gpu_have_udmabuf(void); > void virtio_gpu_init_udmabuf(struct virtio_gpu_simple_resource *res); > -void virtio_gpu_fini_udmabuf(struct virtio_gpu_simple_resource *res); > +void virtio_gpu_fini_udmabuf(VirtIOGPU *g, > + struct virtio_gpu_simple_resource *res); > int virtio_gpu_update_dmabuf(VirtIOGPU *g, > uint32_t scanout_id, > struct virtio_gpu_simple_resource *res, > diff --git a/hw/display/virtio-gpu-udmabuf.c b/hw/display/virtio-gpu-udmabuf.c > index d804f321aa..bd5b44f5fb 100644 > --- a/hw/display/virtio-gpu-udmabuf.c > +++ b/hw/display/virtio-gpu-udmabuf.c > @@ -151,13 +151,6 @@ void virtio_gpu_init_udmabuf(struct > virtio_gpu_simple_resource *res) > res->blob = pdata; > } > > -void virtio_gpu_fini_udmabuf(struct virtio_gpu_simple_resource *res) > -{ > - if (res->remapped) { > - virtio_gpu_destroy_udmabuf(res); > - } > -} > - > static void virtio_gpu_free_dmabuf(VirtIOGPU *g, VGPUDMABuf *dmabuf) > { > struct virtio_gpu_scanout *scanout; > @@ -169,6 +162,24 @@ static void virtio_gpu_free_dmabuf(VirtIOGPU *g, > VGPUDMABuf *dmabuf) > g_free(dmabuf); > } > > +void virtio_gpu_fini_udmabuf(VirtIOGPU *g, struct virtio_gpu_simple_resource > *res) > +{ > + int max_outputs = g->parent_obj.conf.max_outputs; > + int i; > + > + for (i = 0; i < max_outputs; i++) { > + VGPUDMABuf *dmabuf = g->dmabuf.primary[i]; > + > + if (dmabuf && (res->dmabuf_fd != -1) && Maybe add qemu_dmabuf_get_numplanes() > 0 ? > + qemu_dmabuf_get_fds(dmabuf->buf, NULL)[0] == res->dmabuf_fd) { > + qemu_dmabuf_close(dmabuf->buf); > + res->dmabuf_fd = -1; I am not really happy about that we close the underlying fd here before the next destroy, but I don't have an immediate solution > + } > + } > + > + virtio_gpu_destroy_udmabuf(res); > +} > + > static VGPUDMABuf > *virtio_gpu_create_dmabuf(VirtIOGPU *g, > uint32_t scanout_id, > diff --git a/hw/display/virtio-gpu.c b/hw/display/virtio-gpu.c > index 643e91ca2a..b2af861f0d 100644 > --- a/hw/display/virtio-gpu.c > +++ b/hw/display/virtio-gpu.c > @@ -902,7 +902,7 @@ void virtio_gpu_cleanup_mapping(VirtIOGPU *g, > res->addrs = NULL; > > if (res->blob) { > - virtio_gpu_fini_udmabuf(res); > + virtio_gpu_fini_udmabuf(g, res); > } > } > > -- > 2.43.0 > > -- Marc-André Lureau
