This is a note to let you know that I've just added the patch titled vhost_vdpa: fix the missing irq_bypass_unregister_producer() invocation to the 5.11-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: vhost_vdpa-fix-the-missing-irq_bypass_unregister_producer-invocation.patch and it can be found in the queue-5.11 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 4c050286bb202cffd5467c1cba982dff391d62e1 Mon Sep 17 00:00:00 2001 From: Gautam Dawar <gdawar.xilinx@xxxxxxxxx> Date: Wed, 24 Feb 2021 17:18:45 +0530 Subject: vhost_vdpa: fix the missing irq_bypass_unregister_producer() invocation 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 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@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 @@ -906,14 +906,10 @@ 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) Patches currently in stable-queue which might be from gdawar.xilinx@xxxxxxxxx are queue-5.11/vhost_vdpa-fix-the-missing-irq_bypass_unregister_producer-invocation.patch