EDAC, i7core: Fix memleaks and use-after-free on probe and remove

Make sure to free and deregister the addrmatch and chancounts devices
allocated during probe in all error paths. Also fix use-after-free in a
probe error path and in the remove success path where the devices were
being put before before deregistration.

Signed-off-by: Johan Hovold <johan@kernel.org>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: linux-edac <linux-edac@vger.kernel.org>
Fixes: 356f0a30860d ("i7core_edac: change the mem allocation scheme to make Documentation/kobject.txt happy")
Link: http://lkml.kernel.org/r/20180612124335.6420-2-johan@kernel.org
Signed-off-by: Borislav Petkov <bp@suse.de>

drivers/edac/i7core_edac.c

@@ -1177,15 +1177,14 @@ static int i7core_create_sysfs_devices(struct mem_ctl_info *mci)
 
 	rc = device_add(pvt->addrmatch_dev);
 	if (rc < 0)
-		return rc;
+		goto err_put_addrmatch;
 
 	if (!pvt->is_registered) {
 		pvt->chancounts_dev = kzalloc(sizeof(*pvt->chancounts_dev),
 					      GFP_KERNEL);
 		if (!pvt->chancounts_dev) {
-			put_device(pvt->addrmatch_dev);
-			device_del(pvt->addrmatch_dev);
-			return -ENOMEM;
+			rc = -ENOMEM;
+			goto err_del_addrmatch;
 		}
 
 		pvt->chancounts_dev->type = &all_channel_counts_type;
@@ -1199,9 +1198,18 @@ static int i7core_create_sysfs_devices(struct mem_ctl_info *mci)
 
 		rc = device_add(pvt->chancounts_dev);
 		if (rc < 0)
-			return rc;
+			goto err_put_chancounts;
 	}
 	return 0;
+
+err_put_chancounts:
+	put_device(pvt->chancounts_dev);
+err_del_addrmatch:
+	device_del(pvt->addrmatch_dev);
+err_put_addrmatch:
+	put_device(pvt->addrmatch_dev);
+
+	return rc;
 }
 
 static void i7core_delete_sysfs_devices(struct mem_ctl_info *mci)
@@ -1211,11 +1219,11 @@ static void i7core_delete_sysfs_devices(struct mem_ctl_info *mci)
 	edac_dbg(1, "\n");
 
 	if (!pvt->is_registered) {
-		put_device(pvt->chancounts_dev);
 		device_del(pvt->chancounts_dev);
+		put_device(pvt->chancounts_dev);
 	}
-	put_device(pvt->addrmatch_dev);
 	device_del(pvt->addrmatch_dev);
+	put_device(pvt->addrmatch_dev);
 }
 
 /****************************************************************************