[PATCH 5.10 047/157] vhost_vdpa: fix the missing irq_bypass_unregister_producer() invocation

From: Greg Kroah-Hartman
Date: Mon Mar 22 2021 - 08:44:37 EST

From: Gautam Dawar <gdawar.xilinx@xxxxxxxxx>

commit 4c050286bb202cffd5467c1cba982dff391d62e1 upstream.

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

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@xxxxxxxxx>
Acked-by: Jason Wang <jasowang@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20210224114845.104173-1-gdawar.xilinx@xxxxxxxxx
Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
drivers/vhost/vdpa.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)

--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c
@@ -910,14 +910,10 @@ err:

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)