ksmbd: add refcnt to ksmbd_conn struct

BugLink: https://bugs.launchpad.net/bugs/2089884

[ Upstream commit ee426bf ]

When sending an oplock break request, opinfo->conn is used,
But freed ->conn can be used on multichannel.
This patch add a reference count to the ksmbd_conn struct
so that it can be freed when it is no longer used.

Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[koichiroden: dropped a hunk for fs/smb/server/vfs_cache.c since
c8efcc7 ("ksmbd: add support for durable handles v1/v2")
is missing, adjusted context due to missing commit
d1c189c ("ksmbd: use rwsem instead of rwlock for lease break")]
Signed-off-by: Koichiro Den <koichiro.den@canonical.com>
Signed-off-by: Roxana Nicolescu <roxana.nicolescu@canonical.com>

Author: namjaejeon

fs/smb/server/connection.c

@@ -39,7 +39,8 @@ void ksmbd_conn_free(struct ksmbd_conn *conn)
 	xa_destroy(&conn->sessions);
 	kvfree(conn->request_buf);
 	kfree(conn->preauth_info);
-	kfree(conn);
+	if (atomic_dec_and_test(&conn->refcnt))
+		kfree(conn);
 }
 
 /**
@@ -68,6 +69,7 @@ struct ksmbd_conn *ksmbd_conn_alloc(void)
 		conn->um = NULL;
 	atomic_set(&conn->req_running, 0);
 	atomic_set(&conn->r_count, 0);
+	atomic_set(&conn->refcnt, 1);
 	conn->total_credits = 1;
 	conn->outstanding_credits = 0;
 

fs/smb/server/connection.h

@@ -106,6 +106,7 @@ struct ksmbd_conn {
 	bool				signing_negotiated;
 	__le16				signing_algorithm;
 	bool				binding;
+	atomic_t			refcnt;
 };
 
 struct ksmbd_conn_ops {

fs/smb/server/oplock.c

@@ -51,6 +51,7 @@ static struct oplock_info *alloc_opinfo(struct ksmbd_work *work,
 	init_waitqueue_head(&opinfo->oplock_brk);
 	atomic_set(&opinfo->refcount, 1);
 	atomic_set(&opinfo->breaking_cnt, 0);
+	atomic_inc(&opinfo->conn->refcnt);
 
 	return opinfo;
 }
@@ -124,6 +125,8 @@ static void free_opinfo(struct oplock_info *opinfo)
 {
 	if (opinfo->is_lease)
 		free_lease(opinfo);
+	if (opinfo->conn && atomic_dec_and_test(&opinfo->conn->refcnt))
+		kfree(opinfo->conn);
 	kfree(opinfo);
 }
 
@@ -162,9 +165,7 @@ static struct oplock_info *opinfo_get_list(struct ksmbd_inode *ci)
 		if (!atomic_inc_not_zero(&opinfo->refcount))
 			opinfo = NULL;
 		else {
-			atomic_inc(&opinfo->conn->r_count);
 			if (ksmbd_conn_releasing(opinfo->conn)) {
-				atomic_dec(&opinfo->conn->r_count);
 				atomic_dec(&opinfo->refcount);
 				opinfo = NULL;
 			}
@@ -176,26 +177,11 @@ static struct oplock_info *opinfo_get_list(struct ksmbd_inode *ci)
 	return opinfo;
 }
 
-static void opinfo_conn_put(struct oplock_info *opinfo)
+void opinfo_put(struct oplock_info *opinfo)
 {
-	struct ksmbd_conn *conn;
-
 	if (!opinfo)
 		return;
 
-	conn = opinfo->conn;
-	/*
-	 * Checking waitqueue to dropping pending requests on
-	 * disconnection. waitqueue_active is safe because it
-	 * uses atomic operation for condition.
-	 */
-	if (!atomic_dec_return(&conn->r_count) && waitqueue_active(&conn->r_count_q))
-		wake_up(&conn->r_count_q);
-	opinfo_put(opinfo);
-}
-
-void opinfo_put(struct oplock_info *opinfo)
-{
 	if (!atomic_dec_and_test(&opinfo->refcount))
 		return;
 
@@ -1130,15 +1116,12 @@ void smb_send_parent_lease_break_noti(struct ksmbd_file *fp,
 			if (!atomic_inc_not_zero(&opinfo->refcount))
 				continue;
 
-			atomic_inc(&opinfo->conn->r_count);
-			if (ksmbd_conn_releasing(opinfo->conn)) {
-				atomic_dec(&opinfo->conn->r_count);
+			if (ksmbd_conn_releasing(opinfo->conn))
 				continue;
-			}
 
 			read_unlock(&p_ci->m_lock);
 			oplock_break(opinfo, SMB2_OPLOCK_LEVEL_NONE);
-			opinfo_conn_put(opinfo);
+			opinfo_put(opinfo);
 			read_lock(&p_ci->m_lock);
 		}
 	}
@@ -1172,14 +1155,11 @@ void smb_lazy_parent_lease_break_close(struct ksmbd_file *fp)
 			if (!atomic_inc_not_zero(&opinfo->refcount))
 				continue;
 
-			atomic_inc(&opinfo->conn->r_count);
-			if (ksmbd_conn_releasing(opinfo->conn)) {
-				atomic_dec(&opinfo->conn->r_count);
+			if (ksmbd_conn_releasing(opinfo->conn))
 				continue;
-			}
 			read_unlock(&p_ci->m_lock);
 			oplock_break(opinfo, SMB2_OPLOCK_LEVEL_NONE);
-			opinfo_conn_put(opinfo);
+			opinfo_put(opinfo);
 			read_lock(&p_ci->m_lock);
 		}
 	}
@@ -1259,7 +1239,7 @@ int smb_grant_oplock(struct ksmbd_work *work, int req_op_level, u64 pid,
 	prev_opinfo = opinfo_get_list(ci);
 	if (!prev_opinfo ||
 	    (prev_opinfo->level == SMB2_OPLOCK_LEVEL_NONE && lctx)) {
-		opinfo_conn_put(prev_opinfo);
+		opinfo_put(prev_opinfo);
 		goto set_lev;
 	}
 	prev_op_has_lease = prev_opinfo->is_lease;
@@ -1269,19 +1249,19 @@ int smb_grant_oplock(struct ksmbd_work *work, int req_op_level, u64 pid,
 	if (share_ret < 0 &&
 	    prev_opinfo->level == SMB2_OPLOCK_LEVEL_EXCLUSIVE) {
 		err = share_ret;
-		opinfo_conn_put(prev_opinfo);
+		opinfo_put(prev_opinfo);
 		goto err_out;
 	}
 
 	if (prev_opinfo->level != SMB2_OPLOCK_LEVEL_BATCH &&
 	    prev_opinfo->level != SMB2_OPLOCK_LEVEL_EXCLUSIVE) {
-		opinfo_conn_put(prev_opinfo);
+		opinfo_put(prev_opinfo);
 		goto op_break_not_needed;
 	}
 
 	list_add(&work->interim_entry, &prev_opinfo->interim_list);
 	err = oplock_break(prev_opinfo, SMB2_OPLOCK_LEVEL_II);
-	opinfo_conn_put(prev_opinfo);
+	opinfo_put(prev_opinfo);
 	if (err == -ENOENT)
 		goto set_lev;
 	/* Check all oplock was freed by close */
@@ -1344,14 +1324,14 @@ static void smb_break_all_write_oplock(struct ksmbd_work *work,
 		return;
 	if (brk_opinfo->level != SMB2_OPLOCK_LEVEL_BATCH &&
 	    brk_opinfo->level != SMB2_OPLOCK_LEVEL_EXCLUSIVE) {
-		opinfo_conn_put(brk_opinfo);
+		opinfo_put(brk_opinfo);
 		return;
 	}
 
 	brk_opinfo->open_trunc = is_trunc;
 	list_add(&work->interim_entry, &brk_opinfo->interim_list);
 	oplock_break(brk_opinfo, SMB2_OPLOCK_LEVEL_II);
-	opinfo_conn_put(brk_opinfo);
+	opinfo_put(brk_opinfo);
 }
 
 /**
@@ -1380,11 +1360,8 @@ void smb_break_all_levII_oplock(struct ksmbd_work *work, struct ksmbd_file *fp,
 		if (!atomic_inc_not_zero(&brk_op->refcount))
 			continue;
 
-		atomic_inc(&brk_op->conn->r_count);
-		if (ksmbd_conn_releasing(brk_op->conn)) {
-			atomic_dec(&brk_op->conn->r_count);
+		if (ksmbd_conn_releasing(brk_op->conn))
 			continue;
-		}
 
 		rcu_read_unlock();
 		if (brk_op->is_lease && (brk_op->o_lease->state &
@@ -1415,7 +1392,7 @@ void smb_break_all_levII_oplock(struct ksmbd_work *work, struct ksmbd_file *fp,
 		brk_op->open_trunc = is_trunc;
 		oplock_break(brk_op, SMB2_OPLOCK_LEVEL_NONE);
 next:
-		opinfo_conn_put(brk_op);
+		opinfo_put(brk_op);
 		rcu_read_lock();
 	}
 	rcu_read_unlock();