[PATCH v2] vhost vdpa: fix the missing irq_bypass_unregister_producer() invocation

[PATCH v2] vhost vdpa: fix the missing irq_bypass_unregister_producer() invocation

[Gautam Dawar]

[-- Attachment #1.1: Type: text/plain, Size: 1626 bytes --]

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.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=211711
Signed-off-by: Gautam Dawar <gdawar@xilinx.com>

-----
changelog:
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)

[-- Attachment #1.2: Type: text/html, Size: 2050 bytes --]

[-- Attachment #2: Type: text/plain, Size: 183 bytes --]

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

Re: [PATCH v2] vhost vdpa: fix the missing irq_bypass_unregister_producer() invocation

[Jason Wang]

[-- Attachment #1.1: Type: text/plain, Size: 1940 bytes --]


On 2021/2/23 6:00 下午, 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.
>
> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=211711 
> <https://bugzilla.kernel.org/show_bug.cgi?id=211711>
> Signed-off-by: Gautam Dawar <gdawar@xilinx.com <mailto:gdawar@xilinx.com>>
>
> -----
> changelog:
> v1->v2:
>  - Addressed Jason's comment to remove the irq check and use
>    vhost_vdpa_unsetup_vq_irq() to avoid local variable vq
> -----
>

Acked-by: Jason Wang <jasowang@redhat.com>


>
> 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)

[-- Attachment #1.2: Type: text/html, Size: 3541 bytes --]

[-- Attachment #2: Type: text/plain, Size: 183 bytes --]

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

Re: [PATCH v2] vhost vdpa: fix the missing irq_bypass_unregister_producer() invocation

[Michael S. Tsirkin]

On Tue, Feb 23, 2021 at 03:30:45PM +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.
> 
> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=211711
> Signed-off-by: Gautam Dawar <gdawar@xilinx.com>

Could you please repost without HTML? Otherwise git am fails on this patch:

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

Also, which commit introduces the bug? A Fixes: tag would be helpful.

Thanks!

> -----
> changelog:
> 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 v2] vhost vdpa: fix the missing irq_bypass_unregister_producer() invocation

[Gautam Dawar]

On Tue, 23 Feb 2021 at 17:43, Michael S. Tsirkin <mst@redhat.com> wrote:
>
> On Tue, Feb 23, 2021 at 03:30:45PM +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.
> >
> > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=211711
> > Signed-off-by: Gautam Dawar <gdawar@xilinx.com>
>
> Could you please repost without HTML? Otherwise git am fails on this patch:
>
> 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
>
> Also, which commit introduces the bug? A Fixes: tag would be helpful.
>
> Thanks!
>
I've added the fixes tag and submitted patch v3 in plain-text format.
Thanks,
Gautam

> > -----
> > changelog:
> > 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