stable inclusion
from stable-5.10.26
commit 2ea2d3a7980030888acf3e283673594d685430b6
bugzilla: 51363

--------------------------------

commit 4c050286 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: 2cf1ba9a ("vhost_vdpa: implement IRQ offloading in vhost_vdpa")
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=211711Signed-off-by: NGautam Dawar <gdawar.xilinx@gmail.com>
Acked-by: NJason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20210224114845.104173-1-gdawar.xilinx@gmail.comSigned-off-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Acked-by: N  Weilong Chen <chenweilong@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>