[PATCH v3] vhost_vdpa: fix the missing irq_bypass_unregister_producer() invocation

[PATCH v3] vhost_vdpa: fix the missing irq_bypass_unregister_producer() invocation

[Gautam Dawar]

When qemu with vhost-vdpa netdevice is run for the first time, it works well.
But after the VM is powered off, the next qemu run causes kernel panic due to a
NULL pointer dereference in irq_bypass_register_producer().

When the VM is powered off, vhost_vdpa_clean_irq() misses on calling
irq_bypass_unregister_producer() for irq 0 because of the existing check.

This leaves stale producer nodes, which are reset in vhost_vring_call_reset()
when vhost_dev_init() is invoked during the second qemu run.

As the node member of struct irq_bypass_producer is also initialized
to zero, traversal on the producers list causes crash due to NULL pointer
dereference.

Fixes: 2cf1ba9a4d15c ("vhost_vdpa: implement IRQ offloading in vhost_vdpa")
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=211711
Signed-off-by: Gautam Dawar <gdawar@xilinx.com>

-----
changelog:
v2->v3:
 - Re-submitting the patch in plain text format as suggested by Michael
 - Added the fixes tag

v1->v2:
 - Addressed Jason's comment to remove the irq check and use
   vhost_vdpa_unsetup_vq_irq() to avoid local variable vq
-----


diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index 62a9bb0efc55..e00573b87aba 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c
@@ -844,14 +844,10 @@ static int vhost_vdpa_open(struct inode *inode,
struct file *filep)

 static void vhost_vdpa_clean_irq(struct vhost_vdpa *v)
 {
-       struct vhost_virtqueue *vq;
        int i;

-       for (i = 0; i < v->nvqs; i++) {
-               vq = &v->vqs[i];
-               if (vq->call_ctx.producer.irq)
-                       irq_bypass_unregister_producer(&vq->call_ctx.producer);
-       }
+       for (i = 0; i < v->nvqs; i++)
+               vhost_vdpa_unsetup_vq_irq(v, i);
 }

 static int vhost_vdpa_release(struct inode *inode, struct file *filep)
_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization

Re: [PATCH v3] vhost_vdpa: fix the missing irq_bypass_unregister_producer() invocation

[Michael S. Tsirkin]

On Tue, Feb 23, 2021 at 06:15:07PM +0530, Gautam Dawar wrote:
> When qemu with vhost-vdpa netdevice is run for the first time, it works well.
> But after the VM is powered off, the next qemu run causes kernel panic due to a
> NULL pointer dereference in irq_bypass_register_producer().
> 
> When the VM is powered off, vhost_vdpa_clean_irq() misses on calling
> irq_bypass_unregister_producer() for irq 0 because of the existing check.
> 
> This leaves stale producer nodes, which are reset in vhost_vring_call_reset()
> when vhost_dev_init() is invoked during the second qemu run.
> 
> As the node member of struct irq_bypass_producer is also initialized
> to zero, traversal on the producers list causes crash due to NULL pointer
> dereference.
> 
> Fixes: 2cf1ba9a4d15c ("vhost_vdpa: implement IRQ offloading in vhost_vdpa")
> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=211711
> Signed-off-by: Gautam Dawar <gdawar@xilinx.com>


A bit better but still:
Applying: vhost_vdpa: fix the missing irq_bypass_unregister_producer() invocation
error: corrupt patch at line 6
error: could not build fake ancestor
Patch failed at 0001 vhost_vdpa: fix the missing irq_bypass_unregister_producer() invocation
hint: Use 'git am --show-current-patch=diff' to see the failed patch


you also want to include acks you got on the previous versions.

> -----
> changelog:
> v2->v3:
>  - Re-submitting the patch in plain text format as suggested by Michael
>  - Added the fixes tag
> 
> v1->v2:
>  - Addressed Jason's comment to remove the irq check and use
>    vhost_vdpa_unsetup_vq_irq() to avoid local variable vq
> -----
> 
> 
> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> index 62a9bb0efc55..e00573b87aba 100644
> --- a/drivers/vhost/vdpa.c
> +++ b/drivers/vhost/vdpa.c
> @@ -844,14 +844,10 @@ static int vhost_vdpa_open(struct inode *inode,
> struct file *filep)
> 
>  static void vhost_vdpa_clean_irq(struct vhost_vdpa *v)
>  {
> -       struct vhost_virtqueue *vq;
>         int i;
> 
> -       for (i = 0; i < v->nvqs; i++) {
> -               vq = &v->vqs[i];
> -               if (vq->call_ctx.producer.irq)
> -                       irq_bypass_unregister_producer(&vq->call_ctx.producer);
> -       }
> +       for (i = 0; i < v->nvqs; i++)
> +               vhost_vdpa_unsetup_vq_irq(v, i);
>  }
> 
>  static int vhost_vdpa_release(struct inode *inode, struct file *filep)

_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization

Re: [PATCH v3] vhost_vdpa: fix the missing irq_bypass_unregister_producer() invocation

[Gautam Dawar]

Hi Michael,

I've submitted a fresh patch including the ack from Jason and after
testing with git am.

Regards,
Gautam

On Tue, 23 Feb 2021 at 18:20, Michael S. Tsirkin <mst@redhat.com> wrote:
>
> On Tue, Feb 23, 2021 at 06:15:07PM +0530, Gautam Dawar wrote:
> > When qemu with vhost-vdpa netdevice is run for the first time, it works well.
> > But after the VM is powered off, the next qemu run causes kernel panic due to a
> > NULL pointer dereference in irq_bypass_register_producer().
> >
> > When the VM is powered off, vhost_vdpa_clean_irq() misses on calling
> > irq_bypass_unregister_producer() for irq 0 because of the existing check.
> >
> > This leaves stale producer nodes, which are reset in vhost_vring_call_reset()
> > when vhost_dev_init() is invoked during the second qemu run.
> >
> > As the node member of struct irq_bypass_producer is also initialized
> > to zero, traversal on the producers list causes crash due to NULL pointer
> > dereference.
> >
> > Fixes: 2cf1ba9a4d15c ("vhost_vdpa: implement IRQ offloading in vhost_vdpa")
> > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=211711
> > Signed-off-by: Gautam Dawar <gdawar@xilinx.com>
>
>
> A bit better but still:
> Applying: vhost_vdpa: fix the missing irq_bypass_unregister_producer() invocation
> error: corrupt patch at line 6
> error: could not build fake ancestor
> Patch failed at 0001 vhost_vdpa: fix the missing irq_bypass_unregister_producer() invocation
> hint: Use 'git am --show-current-patch=diff' to see the failed patch
>
>
> you also want to include acks you got on the previous versions.
>
> > -----
> > changelog:
> > v2->v3:
> >  - Re-submitting the patch in plain text format as suggested by Michael
> >  - Added the fixes tag
> >
> > v1->v2:
> >  - Addressed Jason's comment to remove the irq check and use
> >    vhost_vdpa_unsetup_vq_irq() to avoid local variable vq
> > -----
> >
> >
> > diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> > index 62a9bb0efc55..e00573b87aba 100644
> > --- a/drivers/vhost/vdpa.c
> > +++ b/drivers/vhost/vdpa.c
> > @@ -844,14 +844,10 @@ static int vhost_vdpa_open(struct inode *inode,
> > struct file *filep)
> >
> >  static void vhost_vdpa_clean_irq(struct vhost_vdpa *v)
> >  {
> > -       struct vhost_virtqueue *vq;
> >         int i;
> >
> > -       for (i = 0; i < v->nvqs; i++) {
> > -               vq = &v->vqs[i];
> > -               if (vq->call_ctx.producer.irq)
> > -                       irq_bypass_unregister_producer(&vq->call_ctx.producer);
> > -       }
> > +       for (i = 0; i < v->nvqs; i++)
> > +               vhost_vdpa_unsetup_vq_irq(v, i);
> >  }
> >
> >  static int vhost_vdpa_release(struct inode *inode, struct file *filep)
>
_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization