diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 8de977c359b1..91678cd01741 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -1979,4 +1979,9 @@ static inline bool cifs_is_referral_server(struct cifs_tcon *tcon,
 	return is_tcon_dfs(tcon) || (ref && (ref->flags & DFSREF_REFERRAL_SERVER));
 }
 
+static inline u64 cifs_flock_len(struct file_lock *fl)
+{
+	return fl->fl_end == OFFSET_MAX ? 0 : fl->fl_end - fl->fl_start + 1;
+}
+
 #endif	/* _CIFS_GLOB_H */
diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index 47e927c4ff8d..a9dccd10e885 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -2558,7 +2558,8 @@ CIFSSMBPosixLock(const unsigned int xid, struct cifs_tcon *tcon,
 
 			pLockData->fl_start = le64_to_cpu(parm_data->start);
 			pLockData->fl_end = pLockData->fl_start +
-					le64_to_cpu(parm_data->length) - 1;
+				(le64_to_cpu(parm_data->length) ?
+				 le64_to_cpu(parm_data->length) - 1 : 0);
 			pLockData->fl_pid = -le32_to_cpu(parm_data->pid);
 		}
 	}
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index d511a78383c3..03f217fa490d 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -1395,7 +1395,7 @@ cifs_push_posix_locks(struct cifsFileInfo *cfile)
 			cifs_dbg(VFS, "Can't push all brlocks!\n");
 			break;
 		}
-		length = 1 + flock->fl_end - flock->fl_start;
+		length = cifs_flock_len(flock);
 		if (flock->fl_type == F_RDLCK || flock->fl_type == F_SHLCK)
 			type = CIFS_RDLCK;
 		else
@@ -1511,7 +1511,7 @@ cifs_getlk(struct file *file, struct file_lock *flock, __u32 type,
 	   bool wait_flag, bool posix_lck, unsigned int xid)
 {
 	int rc = 0;
-	__u64 length = 1 + flock->fl_end - flock->fl_start;
+	__u64 length = cifs_flock_len(flock);
 	struct cifsFileInfo *cfile = (struct cifsFileInfo *)file->private_data;
 	struct cifs_tcon *tcon = tlink_tcon(cfile->tlink);
 	struct TCP_Server_Info *server = tcon->ses->server;
@@ -1609,7 +1609,7 @@ cifs_unlock_range(struct cifsFileInfo *cfile, struct file_lock *flock,
 	struct cifs_tcon *tcon = tlink_tcon(cfile->tlink);
 	struct cifsInodeInfo *cinode = CIFS_I(d_inode(cfile->dentry));
 	struct cifsLockInfo *li, *tmp;
-	__u64 length = 1 + flock->fl_end - flock->fl_start;
+	__u64 length = cifs_flock_len(flock);
 	struct list_head tmp_llist;
 
 	INIT_LIST_HEAD(&tmp_llist);
@@ -1713,7 +1713,7 @@ cifs_setlk(struct file *file, struct file_lock *flock, __u32 type,
 	   unsigned int xid)
 {
 	int rc = 0;
-	__u64 length = 1 + flock->fl_end - flock->fl_start;
+	__u64 length = cifs_flock_len(flock);
 	struct cifsFileInfo *cfile = (struct cifsFileInfo *)file->private_data;
 	struct cifs_tcon *tcon = tlink_tcon(cfile->tlink);
 	struct TCP_Server_Info *server = tcon->ses->server;