[PATCH] virtio-pci: fix virtio_pci_queue_enabled()

[PATCH] virtio-pci: fix virtio_pci_queue_enabled()

[Laurent Vivier]

In legacy mode, virtio_pci_queue_enabled() falls back to
virtio_queue_enabled() to know if the queue is enabled.

But virtio_queue_enabled() calls again virtio_pci_queue_enabled()
if k->queue_enabled is set. This ends in a crash after a stack
overflow.

The problem can be reproduced with
"-device virtio-net-pci,disable-legacy=off,disable-modern=true
 -net tap,vhost=on"

And a look to the backtrace is very explicit:

    ...
    #4  0x000000010029a438 in virtio_queue_enabled ()
    #5  0x0000000100497a9c in virtio_pci_queue_enabled ()
    ...
    #130902 0x000000010029a460 in virtio_queue_enabled ()
    #130903 0x0000000100497a9c in virtio_pci_queue_enabled ()
    #130904 0x000000010029a460 in virtio_queue_enabled ()
    #130905 0x0000000100454a20 in vhost_net_start ()
    ...

This patch fixes the problem by introducing a new function
for the legacy case and calls it from virtio_pci_queue_enabled().
It also calls it from virtio_queue_enabled() to avoid code duplication.

Fixes: f19bcdfedd53 ("virtio-pci: implement queue_enabled method")
Cc: Jason Wang <jasowang@redhat.com>
Cc: Cindy Lu <lulu@redhat.com>
CC: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Laurent Vivier <lvivier@redhat.com>
---
 hw/virtio/virtio-pci.c     | 2 +-
 hw/virtio/virtio.c         | 7 ++++++-
 include/hw/virtio/virtio.h | 1 +
 3 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index ada1101d07bf..4ad3ad81a2cf 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -1116,7 +1116,7 @@ static bool virtio_pci_queue_enabled(DeviceState *d, int n)
         return proxy->vqs[vdev->queue_sel].enabled;
     }
 
-    return virtio_queue_enabled(vdev, n);
+    return virtio_queue_enabled_legacy(vdev, n);
 }
 
 static int virtio_pci_add_mem_cap(VirtIOPCIProxy *proxy,
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 546a198e79b0..e98302521769 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -3309,6 +3309,11 @@ hwaddr virtio_queue_get_desc_addr(VirtIODevice *vdev, int n)
     return vdev->vq[n].vring.desc;
 }
 
+bool virtio_queue_enabled_legacy(VirtIODevice *vdev, int n)
+{
+    return virtio_queue_get_desc_addr(vdev, n) != 0;
+}
+
 bool virtio_queue_enabled(VirtIODevice *vdev, int n)
 {
     BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
@@ -3317,7 +3322,7 @@ bool virtio_queue_enabled(VirtIODevice *vdev, int n)
     if (k->queue_enabled) {
         return k->queue_enabled(qbus->parent, n);
     }
-    return virtio_queue_get_desc_addr(vdev, n) != 0;
+    return virtio_queue_enabled_legacy(vdev, n);
 }
 
 hwaddr virtio_queue_get_avail_addr(VirtIODevice *vdev, int n)
diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
index 198ffc762678..e424df12cf6d 100644
--- a/include/hw/virtio/virtio.h
+++ b/include/hw/virtio/virtio.h
@@ -295,6 +295,7 @@ typedef struct VirtIORNGConf VirtIORNGConf;
                       VIRTIO_F_RING_PACKED, false)
 
 hwaddr virtio_queue_get_desc_addr(VirtIODevice *vdev, int n);
+bool virtio_queue_enabled_legacy(VirtIODevice *vdev, int n);
 bool virtio_queue_enabled(VirtIODevice *vdev, int n);
 hwaddr virtio_queue_get_avail_addr(VirtIODevice *vdev, int n);
 hwaddr virtio_queue_get_used_addr(VirtIODevice *vdev, int n);
-- 
2.26.2

Re: [PATCH] virtio-pci: fix virtio_pci_queue_enabled()

[Richard Henderson]

On 7/27/20 8:33 AM, Laurent Vivier wrote:
> In legacy mode, virtio_pci_queue_enabled() falls back to
> virtio_queue_enabled() to know if the queue is enabled.
> 
> But virtio_queue_enabled() calls again virtio_pci_queue_enabled()
> if k->queue_enabled is set. This ends in a crash after a stack
> overflow.
> 
> The problem can be reproduced with
> "-device virtio-net-pci,disable-legacy=off,disable-modern=true
>  -net tap,vhost=on"
> 
> And a look to the backtrace is very explicit:
> 
>     ...
>     #4  0x000000010029a438 in virtio_queue_enabled ()
>     #5  0x0000000100497a9c in virtio_pci_queue_enabled ()
>     ...
>     #130902 0x000000010029a460 in virtio_queue_enabled ()
>     #130903 0x0000000100497a9c in virtio_pci_queue_enabled ()
>     #130904 0x000000010029a460 in virtio_queue_enabled ()
>     #130905 0x0000000100454a20 in vhost_net_start ()
>     ...
> 
> This patch fixes the problem by introducing a new function
> for the legacy case and calls it from virtio_pci_queue_enabled().
> It also calls it from virtio_queue_enabled() to avoid code duplication.
> 
> Fixes: f19bcdfedd53 ("virtio-pci: implement queue_enabled method")
> Cc: Jason Wang <jasowang@redhat.com>
> Cc: Cindy Lu <lulu@redhat.com>
> CC: Michael S. Tsirkin <mst@redhat.com>
> Signed-off-by: Laurent Vivier <lvivier@redhat.com>
> ---

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~

Re: [PATCH] virtio-pci: fix virtio_pci_queue_enabled()

[Jason Wang]

On 2020/7/27 下午11:33, Laurent Vivier wrote:
> In legacy mode, virtio_pci_queue_enabled() falls back to
> virtio_queue_enabled() to know if the queue is enabled.
>
> But virtio_queue_enabled() calls again virtio_pci_queue_enabled()
> if k->queue_enabled is set. This ends in a crash after a stack
> overflow.
>
> The problem can be reproduced with
> "-device virtio-net-pci,disable-legacy=off,disable-modern=true
>   -net tap,vhost=on"
>
> And a look to the backtrace is very explicit:
>
>      ...
>      #4  0x000000010029a438 in virtio_queue_enabled ()
>      #5  0x0000000100497a9c in virtio_pci_queue_enabled ()
>      ...
>      #130902 0x000000010029a460 in virtio_queue_enabled ()
>      #130903 0x0000000100497a9c in virtio_pci_queue_enabled ()
>      #130904 0x000000010029a460 in virtio_queue_enabled ()
>      #130905 0x0000000100454a20 in vhost_net_start ()
>      ...
>
> This patch fixes the problem by introducing a new function
> for the legacy case and calls it from virtio_pci_queue_enabled().
> It also calls it from virtio_queue_enabled() to avoid code duplication.
>
> Fixes: f19bcdfedd53 ("virtio-pci: implement queue_enabled method")
> Cc: Jason Wang <jasowang@redhat.com>
> Cc: Cindy Lu <lulu@redhat.com>
> CC: Michael S. Tsirkin <mst@redhat.com>
> Signed-off-by: Laurent Vivier <lvivier@redhat.com>


Queued for rc2.

Thanks


> ---
>   hw/virtio/virtio-pci.c     | 2 +-
>   hw/virtio/virtio.c         | 7 ++++++-
>   include/hw/virtio/virtio.h | 1 +
>   3 files changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> index ada1101d07bf..4ad3ad81a2cf 100644
> --- a/hw/virtio/virtio-pci.c
> +++ b/hw/virtio/virtio-pci.c
> @@ -1116,7 +1116,7 @@ static bool virtio_pci_queue_enabled(DeviceState *d, int n)
>           return proxy->vqs[vdev->queue_sel].enabled;
>       }
>   
> -    return virtio_queue_enabled(vdev, n);
> +    return virtio_queue_enabled_legacy(vdev, n);
>   }
>   
>   static int virtio_pci_add_mem_cap(VirtIOPCIProxy *proxy,
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index 546a198e79b0..e98302521769 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -3309,6 +3309,11 @@ hwaddr virtio_queue_get_desc_addr(VirtIODevice *vdev, int n)
>       return vdev->vq[n].vring.desc;
>   }
>   
> +bool virtio_queue_enabled_legacy(VirtIODevice *vdev, int n)
> +{
> +    return virtio_queue_get_desc_addr(vdev, n) != 0;
> +}
> +
>   bool virtio_queue_enabled(VirtIODevice *vdev, int n)
>   {
>       BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
> @@ -3317,7 +3322,7 @@ bool virtio_queue_enabled(VirtIODevice *vdev, int n)
>       if (k->queue_enabled) {
>           return k->queue_enabled(qbus->parent, n);
>       }
> -    return virtio_queue_get_desc_addr(vdev, n) != 0;
> +    return virtio_queue_enabled_legacy(vdev, n);
>   }
>   
>   hwaddr virtio_queue_get_avail_addr(VirtIODevice *vdev, int n)
> diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
> index 198ffc762678..e424df12cf6d 100644
> --- a/include/hw/virtio/virtio.h
> +++ b/include/hw/virtio/virtio.h
> @@ -295,6 +295,7 @@ typedef struct VirtIORNGConf VirtIORNGConf;
>                         VIRTIO_F_RING_PACKED, false)
>   
>   hwaddr virtio_queue_get_desc_addr(VirtIODevice *vdev, int n);
> +bool virtio_queue_enabled_legacy(VirtIODevice *vdev, int n);
>   bool virtio_queue_enabled(VirtIODevice *vdev, int n);
>   hwaddr virtio_queue_get_avail_addr(VirtIODevice *vdev, int n);
>   hwaddr virtio_queue_get_used_addr(VirtIODevice *vdev, int n);

Re: [PATCH] virtio-pci: fix virtio_pci_queue_enabled()

[Michael S. Tsirkin]

On Tue, Jul 28, 2020 at 11:55:16AM +0800, Jason Wang wrote:
> 
> On 2020/7/27 下午11:33, Laurent Vivier wrote:
> > In legacy mode, virtio_pci_queue_enabled() falls back to
> > virtio_queue_enabled() to know if the queue is enabled.
> > 
> > But virtio_queue_enabled() calls again virtio_pci_queue_enabled()
> > if k->queue_enabled is set. This ends in a crash after a stack
> > overflow.
> > 
> > The problem can be reproduced with
> > "-device virtio-net-pci,disable-legacy=off,disable-modern=true
> >   -net tap,vhost=on"
> > 
> > And a look to the backtrace is very explicit:
> > 
> >      ...
> >      #4  0x000000010029a438 in virtio_queue_enabled ()
> >      #5  0x0000000100497a9c in virtio_pci_queue_enabled ()
> >      ...
> >      #130902 0x000000010029a460 in virtio_queue_enabled ()
> >      #130903 0x0000000100497a9c in virtio_pci_queue_enabled ()
> >      #130904 0x000000010029a460 in virtio_queue_enabled ()
> >      #130905 0x0000000100454a20 in vhost_net_start ()
> >      ...
> > 
> > This patch fixes the problem by introducing a new function
> > for the legacy case and calls it from virtio_pci_queue_enabled().
> > It also calls it from virtio_queue_enabled() to avoid code duplication.
> > 
> > Fixes: f19bcdfedd53 ("virtio-pci: implement queue_enabled method")
> > Cc: Jason Wang <jasowang@redhat.com>
> > Cc: Cindy Lu <lulu@redhat.com>
> > CC: Michael S. Tsirkin <mst@redhat.com>
> > Signed-off-by: Laurent Vivier <lvivier@redhat.com>
> 
> 
> Queued for rc2.
> 
> Thanks

Oh I didn't realise you are merging virtio patches.
If you do, pls include this tag:

Reviewed-by: Michael S. Tsirkin <mst@redhat.com>


> 
> > ---
> >   hw/virtio/virtio-pci.c     | 2 +-
> >   hw/virtio/virtio.c         | 7 ++++++-
> >   include/hw/virtio/virtio.h | 1 +
> >   3 files changed, 8 insertions(+), 2 deletions(-)
> > 
> > diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> > index ada1101d07bf..4ad3ad81a2cf 100644
> > --- a/hw/virtio/virtio-pci.c
> > +++ b/hw/virtio/virtio-pci.c
> > @@ -1116,7 +1116,7 @@ static bool virtio_pci_queue_enabled(DeviceState *d, int n)
> >           return proxy->vqs[vdev->queue_sel].enabled;
> >       }
> > -    return virtio_queue_enabled(vdev, n);
> > +    return virtio_queue_enabled_legacy(vdev, n);
> >   }
> >   static int virtio_pci_add_mem_cap(VirtIOPCIProxy *proxy,
> > diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> > index 546a198e79b0..e98302521769 100644
> > --- a/hw/virtio/virtio.c
> > +++ b/hw/virtio/virtio.c
> > @@ -3309,6 +3309,11 @@ hwaddr virtio_queue_get_desc_addr(VirtIODevice *vdev, int n)
> >       return vdev->vq[n].vring.desc;
> >   }
> > +bool virtio_queue_enabled_legacy(VirtIODevice *vdev, int n)
> > +{
> > +    return virtio_queue_get_desc_addr(vdev, n) != 0;
> > +}
> > +
> >   bool virtio_queue_enabled(VirtIODevice *vdev, int n)
> >   {
> >       BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
> > @@ -3317,7 +3322,7 @@ bool virtio_queue_enabled(VirtIODevice *vdev, int n)
> >       if (k->queue_enabled) {
> >           return k->queue_enabled(qbus->parent, n);
> >       }
> > -    return virtio_queue_get_desc_addr(vdev, n) != 0;
> > +    return virtio_queue_enabled_legacy(vdev, n);
> >   }
> >   hwaddr virtio_queue_get_avail_addr(VirtIODevice *vdev, int n)
> > diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
> > index 198ffc762678..e424df12cf6d 100644
> > --- a/include/hw/virtio/virtio.h
> > +++ b/include/hw/virtio/virtio.h
> > @@ -295,6 +295,7 @@ typedef struct VirtIORNGConf VirtIORNGConf;
> >                         VIRTIO_F_RING_PACKED, false)
> >   hwaddr virtio_queue_get_desc_addr(VirtIODevice *vdev, int n);
> > +bool virtio_queue_enabled_legacy(VirtIODevice *vdev, int n);
> >   bool virtio_queue_enabled(VirtIODevice *vdev, int n);
> >   hwaddr virtio_queue_get_avail_addr(VirtIODevice *vdev, int n);
> >   hwaddr virtio_queue_get_used_addr(VirtIODevice *vdev, int n);