On Fri, Sep 27, 2024 at 02:51:38AM +0000, Mark-PK Tsai (蔡沛剛) wrote:
> Hi,
>
> Could someone help to review it or provide suggestions?
> Any comments are welcome.
>
> This patch is intended to allow the rproc driver to handle the
> following use-after-free issue:
>
>
> ### UAF log
What does "UAF" means?
> [ 337.540275][ T470] virtqueue_add.llvm.10153462284424984632+0xb48/0
> xcc4
> [ 337.546969][ T470] virtqueue_add_inbuf+0x44/0x6c
> <--- vqs are freed in vring_del_virtqueue
> [ 337.551755][ T470] rpmsg_recv_done+0x1fc/0x2c4 [virtio_rpmsg_bus]
> [ 337.558023][ T470] vring_interrupt+0xa0/0xe0
> [ 337.562462][ T470] rproc_vq_interrupt+0x34/0x48
> [ 337.567160][ T470] handle_event+0x28/0x48 [mtk_pqu_rproc]
> [ 337.572742][ T470] irq_thread_fn+0x4c/0xcc
> [ 337.577009][ T470] irq_thread+0x1d0/0x360
> [ 337.581189][ T470] kthread+0x168/0x1cc
> [ 337.585107][ T470] ret_from_fork+0x10/0x20
>
> ### stack trace of obj free
> [ 339.253063][ T470] die_helper: <-
> vring_del_virtqueue+0x16c/0x198
> [ 339.259757][ T470] die_helper: <- kfree+0x274/0x35c
> [ 339.265236][ T470] die_helper: <-
> vring_del_virtqueue+0x16c/0x198
> [ 339.271929][ T470] die_helper: <-
> rproc_virtio_del_vqs+0x3c/0x58
> [ 339.278535][ T470] die_helper: <- rpmsg_remove+0x8c/0x12c
> [virtio_rpmsg_bus]
> [ 339.286189][ T470] die_helper: <-
> virtio_dev_remove+0x64/0x174
> [ 339.292622][ T470] die_helper: <-
> device_release_driver_internal+0x1a8/0x32c
> [ 339.300270][ T470] die_helper: <-
> bus_remove_device+0x130/0x160
> [ 339.306789][ T470] die_helper: <- device_del+0x224/0x518
> [ 339.312702][ T470] die_helper: <- device_unregister+0x20/0x3c
> [ 339.319047][ T470] die_helper: <-
> rproc_remove_virtio_dev+0x20/0x44
> [ 339.325913][ T470] die_helper: <-
> device_for_each_child+0x84/0x100
> [ 339.332696][ T470] die_helper: <-
> rproc_vdev_do_stop+0x30/0x5c
> [ 339.339130][ T470] die_helper: <- rproc_stop+0xcc/0x200
>
None of the above is showing me where this use-after-free happens.
> On Fri, 2024-09-20 at 17:16 +0800, Mark-PK Tsai wrote:
> > Add synchornize_cbs to rproc_virtio_config_ops and a
> > synchronize_vqs callback to the rproc_ops to ensure vqs'
> > state changes are visible in vring_interrupts when the vq is
> > broken or removed.
> >
> > And when VIRTIO_HARDEN_NOTIFICATION is not set, call
> > rproc_virtio_synchronize_cbs directly in __rproc_virtio_del_vqs
> > before virtqueue is free to ensure that rproc_vq_interrupt is
> > aware of the virtqueue removal.
> >
> > The synchronized_vqs is expected to be implemented in rproc
> > driver to ensure that all previous vring_interrupts are handled
> > before the vqs are marked as broken or removed.
> >
> > Signed-off-by: Mark-PK Tsai <mark-pk.tsai@xxxxxxxxxxxx>
> > ---
> > drivers/remoteproc/remoteproc_virtio.c | 12 ++++++++++++
> > include/linux/remoteproc.h | 4 ++++
> > 2 files changed, 16 insertions(+)
> >
> > diff --git a/drivers/remoteproc/remoteproc_virtio.c
> > b/drivers/remoteproc/remoteproc_virtio.c
> > index d3f39009b28e..e18258b69851 100644
> > --- a/drivers/remoteproc/remoteproc_virtio.c
> > +++ b/drivers/remoteproc/remoteproc_virtio.c
> > @@ -74,6 +74,14 @@ static bool rproc_virtio_notify(struct virtqueue
> > *vq)
> > return true;
> > }
> >
> > +static void rproc_virtio_synchronize_cbs(struct virtio_device *vdev)
> > +{
> > + struct rproc *rproc = vdev_to_rproc(vdev);
> > +
> > + if (rproc->ops->synchronize_vqs)
> > + rproc->ops->synchronize_vqs(rproc);
> > +}
> > +
> > /**
> > * rproc_vq_interrupt() - tell remoteproc that a virtqueue is
> > interrupted
> > * @rproc: handle to the remote processor
> > @@ -171,6 +179,9 @@ static void __rproc_virtio_del_vqs(struct
> > virtio_device *vdev)
> > list_for_each_entry_safe(vq, n, &vdev->vqs, list) {
> > rvring = vq->priv;
> > rvring->vq = NULL;
> > +#ifndef CONFIG_VIRTIO_HARDEN_NOTIFICATION
> > + rproc_virtio_synchronize_cbs(vdev);
> > +#endif
> > vring_del_virtqueue(vq);
> > }
> > }
> > @@ -334,6 +345,7 @@ static const struct virtio_config_ops
> > rproc_virtio_config_ops = {
> > .get_status = rproc_virtio_get_status,
> > .get = rproc_virtio_get,
> > .set = rproc_virtio_set,
> > + .synchronize_cbs = rproc_virtio_synchronize_cbs,
Where and when is this called?
This patch is very confusing and doesn't have a user. As such it is
impossible for me to understand what is going on.
Thanks,
Mathieu
> > };
> >
> > /*
> > diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
> > index b4795698d8c2..73901678ac7d 100644
> > --- a/include/linux/remoteproc.h
> > +++ b/include/linux/remoteproc.h
> > @@ -381,6 +381,9 @@ enum rsc_handling_status {
> > * @panic: optional callback to react to system panic, core will
> > delay
> > * panic at least the returned number of milliseconds
> > * @coredump: collect firmware dump after the subsystem is
> > shutdown
> > + * @synchronize_vqs: optional callback to guarantee all memory
> > operations
> > + * on the virtqueue before it are visible to the
> > + * rproc_vq_interrupt().
> > */
> > struct rproc_ops {
> > int (*prepare)(struct rproc *rproc);
> > @@ -403,6 +406,7 @@ struct rproc_ops {
> > u64 (*get_boot_addr)(struct rproc *rproc, const struct firmware
> > *fw);
> > unsigned long (*panic)(struct rproc *rproc);
> > void (*coredump)(struct rproc *rproc);
> > + void (*synchronize_vqs)(struct rproc *rproc);
> > };
> >
> > /**
>
