On Tue, 23 Feb 2021 at 17:43, Michael S. Tsirkin <[email protected]> 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 <[email protected]>
>
> 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)
>
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