mwifiex: reset card->adapter during device unregister

card->adapter gets initialized in mwifiex_register_dev(). As it's not
cleared in mwifiex_unregister_dev(), we may end up accessing the memory
which is already free in below scenario.

Scenario: Driver initialization is failed due to incorrect firmware or
some other reason. Meanwhile device reboot/unload occurs.

This is safe, now that we've properly synchronized suspend() and
remove() with the FW initialization thread; now that code can simply
check for 'card->adapter == NULL' and exit safely.
Signed-off-by: Xinming Hu <huxm@marvell.com>
Tested-by: Xinming Hu <huxm@marvell.com>
Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/marvell/mwifiex/pcie.c

@@ -3042,6 +3042,7 @@ static void mwifiex_unregister_dev(struct mwifiex_adapter *adapter)
 			if (card->msi_enable)
 				pci_disable_msi(pdev);
 	       }
+		card->adapter = NULL;
 	}
 }
 

drivers/net/wireless/marvell/mwifiex/sdio.c

@@ -2017,6 +2017,7 @@ mwifiex_unregister_dev(struct mwifiex_adapter *adapter)
 	struct sdio_mmc_card *card = adapter->card;
 
 	if (adapter->card) {
+		card->adapter = NULL;
 		sdio_claim_host(card->func);
 		sdio_disable_func(card->func);
 		sdio_release_host(card->func);