1 files changed, 45 insertions, 27 deletions

diff --git a/fs/smb/server/oplock.c b/fs/smb/server/oplock.c
index 393a4ae47cc1..9b2bb8764a80 100644
--- a/fs/smb/server/oplock.c
+++ b/fs/smb/server/oplock.c
@@ -82,11 +82,19 @@ static void lease_del_list(struct oplock_info *opinfo)
 	spin_unlock(&lb->lb_lock);
 }
 
-static void lb_add(struct lease_table *lb)
+static struct lease_table *alloc_lease_table(struct oplock_info *opinfo)
 {
-	write_lock(&lease_list_lock);
-	list_add(&lb->l_entry, &lease_table_list);
-	write_unlock(&lease_list_lock);
+	struct lease_table *lb;
+
+	lb = kmalloc_obj(struct lease_table, KSMBD_DEFAULT_GFP);
+	if (!lb)
+		return NULL;
+
+	memcpy(lb->client_guid, opinfo->conn->ClientGUID,
+	       SMB2_CLIENT_GUID_SIZE);
+	INIT_LIST_HEAD(&lb->lease_list);
+	spin_lock_init(&lb->lb_lock);
+	return lb;
 }
 
 static int alloc_lease(struct oplock_info *opinfo, struct lease_ctx_info *lctx)
@@ -1042,34 +1050,27 @@ static void copy_lease(struct oplock_info *op1, struct oplock_info *op2)
 	lease2->version = lease1->version;
 }
 
-static int add_lease_global_list(struct oplock_info *opinfo)
+static void add_lease_global_list(struct oplock_info *opinfo,
+				  struct lease_table *new_lb)
 {
 	struct lease_table *lb;
 
-	read_lock(&lease_list_lock);
+	write_lock(&lease_list_lock);
 	list_for_each_entry(lb, &lease_table_list, l_entry) {
 		if (!memcmp(lb->client_guid, opinfo->conn->ClientGUID,
 			    SMB2_CLIENT_GUID_SIZE)) {
 			opinfo->o_lease->l_lb = lb;
 			lease_add_list(opinfo);
-			read_unlock(&lease_list_lock);
-			return 0;
+			write_unlock(&lease_list_lock);
+			kfree(new_lb);
+			return;
 		}
 	}
-	read_unlock(&lease_list_lock);
 
-	lb = kmalloc_obj(struct lease_table, KSMBD_DEFAULT_GFP);
-	if (!lb)
-		return -ENOMEM;
-
-	memcpy(lb->client_guid, opinfo->conn->ClientGUID,
-	       SMB2_CLIENT_GUID_SIZE);
-	INIT_LIST_HEAD(&lb->lease_list);
-	spin_lock_init(&lb->lb_lock);
-	opinfo->o_lease->l_lb = lb;
+	opinfo->o_lease->l_lb = new_lb;
 	lease_add_list(opinfo);
-	lb_add(lb);
-	return 0;
+	list_add(&new_lb->l_entry, &lease_table_list);
+	write_unlock(&lease_list_lock);
 }
 
 static void set_oplock_level(struct oplock_info *opinfo, int level,
@@ -1189,6 +1190,7 @@ int smb_grant_oplock(struct ksmbd_work *work, int req_op_level, u64 pid,
 	int err = 0;
 	struct oplock_info *opinfo = NULL, *prev_opinfo = NULL;
 	struct ksmbd_inode *ci = fp->f_ci;
+	struct lease_table *new_lb = NULL;
 	bool prev_op_has_lease;
 	__le32 prev_op_state = 0;
 
@@ -1291,21 +1293,37 @@ set_lev:
 	set_oplock_level(opinfo, req_op_level, lctx);
 
 out:
-	opinfo_count_inc(fp);
-	opinfo_add(opinfo, fp);
-
+	/*
+	 * Set o_fp before any publication so that concurrent readers
+	 * (e.g. find_same_lease_key() on the lease list) that
+	 * dereference opinfo->o_fp don't hit a NULL pointer.
+	 *
+	 * Keep the original publication order so concurrent opens can
+	 * still observe the in-flight grant via ci->m_op_list, but make
+	 * everything after opinfo_add() no-fail by preallocating any new
+	 * lease_table first.
+	 */
+	opinfo->o_fp = fp;
 	if (opinfo->is_lease) {
-		err = add_lease_global_list(opinfo);
-		if (err)
+		new_lb = alloc_lease_table(opinfo);
+		if (!new_lb) {
+			err = -ENOMEM;
 			goto err_out;
+		}
 	}
 
+	opinfo_count_inc(fp);
+	opinfo_add(opinfo, fp);
+
+	if (opinfo->is_lease)
+		add_lease_global_list(opinfo, new_lb);
+
 	rcu_assign_pointer(fp->f_opinfo, opinfo);
-	opinfo->o_fp = fp;
 
 	return 0;
 err_out:
-	__free_opinfo(opinfo);
+	kfree(new_lb);
+	opinfo_put(opinfo);
 	return err;
 }