driver core: auxiliary bus: Fix auxiliary bus shutdown null auxdrv ptr

mainline inclusion
from mainline-v5.11-rc1
commit 784b2c48
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I4O662


CVE: NA

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If the probe of the auxdrv failed, the device->driver is set to NULL.
During kernel shutdown, the bus shutdown will call auxdrv->shutdown and
cause an invalid ptr dereference. Add check to make sure device->driver is
not NULL before we proceed.

Fixes: 7de3697e ("Add auxiliary bus support")
Cc: Dave Ertman <david.m.ertman@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Link: https://lore.kernel.org/r/160710040926.1889434.8840329810698403478.stgit@djiang5-desk3.ch.intel.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Yuanzheng Song <songyuanzheng@huawei.com>
Reviewed-by: Kefeng <Wang&lt;wangkefeng.wang@huawei.com>
Reviewed-by: Hanjun Guo <guohanjun@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>