wifi: iwlwifi: pcie: fix possible NULL pointer dereference

[ Upstream commit b655b9a ]

It is possible that iwl_pci_probe() will fail and free the trans,
then afterwards iwl_pci_remove() will be called and crash by trying
to access trans which is already freed, fix it.

iwlwifi 0000:01:00.0: Detected crf-id 0xa5a5a5a2, cnv-id 0xa5a5a5a2
		      wfpm id 0xa5a5a5a2
iwlwifi 0000:01:00.0: Can't find a correct rfid for crf id 0x5a2
...
BUG: kernel NULL pointer dereference, address: 0000000000000028
...
RIP: 0010:iwl_pci_remove+0x12/0x30 [iwlwifi]
pci_device_remove+0x3e/0xb0
device_release_driver_internal+0x103/0x1f0
driver_detach+0x4c/0x90
bus_remove_driver+0x5c/0xd0
driver_unregister+0x31/0x50
pci_unregister_driver+0x40/0x90
iwl_pci_unregister_driver+0x15/0x20 [iwlwifi]
__exit_compat+0x9/0x98 [iwlwifi]
__x64_sys_delete_module+0x147/0x260

Signed-off-by: Daniel Gabay <daniel.gabay@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230413213309.082f6e21341b.I0db21d7fa9a828d571ca886713bd0b5d0b6e1e5c@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/net/wireless/intel/iwlwifi/pcie/drv.c

@@ -1685,6 +1685,9 @@ static void iwl_pci_remove(struct pci_dev *pdev)
 {
 	struct iwl_trans *trans = pci_get_drvdata(pdev);
 
+	if (!trans)
+		return;
+
 	iwl_drv_stop(trans->drv);
 
 	iwl_trans_pcie_free(trans);