md: Fix stray --cluster-confirm crash

A --cluster-confirm without an --add (by another node) can
crash the kernel.

Fix it by guarding it using a state.

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: NeilBrown <neilb@suse.de>

3 files changed, 21 insertions, 4 deletions

diff --git a/drivers/md/md-cluster.c b/drivers/md/md-cluster.c
index 03e521a9ca7d..96679b22cfc0 100644
--- a/drivers/md/md-cluster.c
+++ b/drivers/md/md-cluster.c
@@ -42,6 +42,10 @@ struct resync_info {
         __le64 hi;
 };
 
+/* md_cluster_info flags */
+#define         MD_CLUSTER_WAITING_FOR_NEWDISK          1
+
+
 struct md_cluster_info {
         /* dlm lock space and resources for clustered raid. */
         dlm_lockspace_t *lockspace;
@@ -61,6 +65,7 @@ struct md_cluster_info {
         struct dlm_lock_resource *no_new_dev_lockres;
         struct md_thread *recv_thread;
         struct completion newdisk_completion;
+        unsigned long state;
 };
 
 enum msg_type {
@@ -380,9 +385,11 @@ static void process_add_new_disk(struct mddev *mddev, struct cluster_msg *cmsg)
         snprintf(raid_slot, 16, "RAID_DISK=%d", cmsg->raid_slot);
         pr_info("%s:%d Sending kobject change with %s and %s\n", __func__, __LINE__, disk_uuid, raid_slot);
         init_completion(&cinfo->newdisk_completion);
+        set_bit(MD_CLUSTER_WAITING_FOR_NEWDISK, &cinfo->state);
         kobject_uevent_env(&disk_to_dev(mddev->gendisk)->kobj, KOBJ_CHANGE, envp);
         wait_for_completion_timeout(&cinfo->newdisk_completion,
                         NEW_DEV_TIMEOUT);
+        clear_bit(MD_CLUSTER_WAITING_FOR_NEWDISK, &cinfo->state);
 }
 
 
@@ -832,13 +839,19 @@ static int add_new_disk_finish(struct mddev *mddev)
         return ret;
 }
 
-static void new_disk_ack(struct mddev *mddev, bool ack)
+static int new_disk_ack(struct mddev *mddev, bool ack)
 {
         struct md_cluster_info *cinfo = mddev->cluster_info;
 
+        if (!test_bit(MD_CLUSTER_WAITING_FOR_NEWDISK, &cinfo->state)) {
+                pr_warn("md-cluster(%s): Spurious cluster confirmation\n", mdname(mddev));
+                return -EINVAL;
+        }
+
         if (ack)
                 dlm_unlock_sync(cinfo->no_new_dev_lockres);
         complete(&cinfo->newdisk_completion);
+        return 0;
 }
 
 static struct md_cluster_operations cluster_ops = {
diff --git a/drivers/md/md-cluster.h b/drivers/md/md-cluster.h
index 60d7e58964f5..7417133c4295 100644
--- a/drivers/md/md-cluster.h
+++ b/drivers/md/md-cluster.h
@@ -21,7 +21,7 @@ struct md_cluster_operations {
         int (*area_resyncing)(struct mddev *mddev, sector_t lo, sector_t hi);
         int (*add_new_disk_start)(struct mddev *mddev, struct md_rdev *rdev);
         int (*add_new_disk_finish)(struct mddev *mddev);
-        void (*new_disk_ack)(struct mddev *mddev, bool ack);
+        int (*new_disk_ack)(struct mddev *mddev, bool ack);
 };
 
 #endif /* _MD_CLUSTER_H */
diff --git a/drivers/md/md.c b/drivers/md/md.c
index ae3432e57ccb..eb6f92e57ab6 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -5755,7 +5755,7 @@ static int add_new_disk(struct mddev *mddev, mdu_disk_info_t *info)
 
         if (mddev_is_clustered(mddev) &&
                 !(info->state & ((1 << MD_DISK_CLUSTER_ADD) | (1 << MD_DISK_CANDIDATE)))) {
-                pr_err("%s: Cannot add to clustered mddev. Try --cluster-add\n",
+                pr_err("%s: Cannot add to clustered mddev.\n",
                                mdname(mddev));
                 return -EINVAL;
         }
@@ -5853,7 +5853,11 @@ static int add_new_disk(struct mddev *mddev, mdu_disk_info_t *info)
                         if (info->state & (1 << MD_DISK_CANDIDATE)) {
                                 /* Through --cluster-confirm */
                                 set_bit(Candidate, &rdev->flags);
-                                md_cluster_ops->new_disk_ack(mddev, true);
+                                err = md_cluster_ops->new_disk_ack(mddev, true);
+                                if (err) {
+                                        export_rdev(rdev);
+                                        return err;
+                                }
                         } else if (info->state & (1 << MD_DISK_CLUSTER_ADD)) {
                                 /* --add initiated by this node */
                                 err = md_cluster_ops->add_new_disk_start(mddev, rdev);