spi: rpc-if: Fix use-after-free on unbind

stable inclusion
from stable-5.10.4
commit 11b81d94f8df34e8bff60e51d1162d7f11ae49d6
bugzilla: 46903

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

commit 393f981c upstream.

rpcif_spi_remove() accesses the driver's private data after calling
spi_unregister_controller() even though that function releases the last
reference on the spi_controller and thereby frees the private data.

Fix by switching over to the new devm_spi_alloc_master() helper which
keeps the private data accessible until the driver has unbound.

Fixes: eb8d6d46 ("spi: add Renesas RPC-IF driver")
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: <stable@vger.kernel.org> # v5.9+: 5e844cc3: spi: Introduce device-managed SPI controller allocation
Cc: <stable@vger.kernel.org> # v5.9+
Cc: Sergei Shtylyov <s.shtylyov@omprussia.ru>
Link: https://lore.kernel.org/r/c5da472c28021da2f6517441685cef033d40b140.1607286887.git.lukas@wunner.de


Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Signed-off-by: Chen Jun <chenjun102@huawei.com>
Acked-by: Xie XiuQi <xiexiuqi@huawei.com>