In the Linux kernel, the following vulnerability has been resolved: nvmet: fix NULL pointer dereference in nvmet_execute_identify_ns_zns()

In the Linux kernel, the following vulnerability has been resolved:

nvmet: fix NULL pointer dereference in nvmet_execute_identify_ns_zns()

When a host issues an Identify command with CNS 05h (I/O Command Set
specific Identify Namespace) and CSI 02h (ZNS) targeting a file-backed
namespace, nvmet_execute_identify_ns_zns() calls bdev_is_zoned() on
req->ns->bdev. A file-backed namespace has no block device, so
req->ns->bdev is NULL and bdev_is_zoned() dereferences it, oopsing.

The I/O command set is selected by the host-supplied CSI field and the
command is routed here whenever CONFIG_BLK_DEV_ZONED is enabled,
independent of the namespace backing type, so any file-backed namespace
is exposed.

Reject the command with Invalid Field when the namespace is not backed
by a block device.