commit 77b6d09f4ae66d42cd63b121af67780ae3d1a5e9 upstream.

Make sure res does not contain random value if the call to
sr_read_cmd fails for some reason.

Reported-by: syzbot+f1842130bbcfb335bac1@syzkaller.appspotmail.com
Signed-off-by: NValentin Vidic <vvidic@valentin-vidic.from.hr>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>