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@xxxxxxxxxx>
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)
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