vhost: use kzalloc() instead of kmalloc() followed by memset()

mainline inclusion
from mainline-v6.4-rc6
commit 4d8df0f5
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I8UW3U
CVE: CVE-2024-0340

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=4d8df0f5f79f747d75a7d356d9b9ea40a4e4c8a9



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

Use kzalloc() to allocate new zeroed out msg node instead of
memsetting a node allocated with kmalloc().

Signed-off-by: Prathu Baronia <prathubaronia2011@gmail.com>
Message-Id: <20230522085019.42914-1-prathubaronia2011@gmail.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Guo Mengqi <guomengqi3@huawei.com>