From: ASANO Masahiro <masano@tnes.nec.co.jp>
Date: Thu, 22 Dec 2005 04:24:54 +0000 (+0900)
Subject: [PATCH] fix posix lock on NFS
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=0800c5f7a499a8961c3868e95cc4cf1715166457;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git

[PATCH] fix posix lock on NFS

NFS client prevents mandatory lock, but there is a flaw on it; Locks are
possibly left if the mode is changed while locking.

This permits unlocking even if the mandatory lock bits are set.

Signed-off-by: ASANO Masahiro <masano@tnes.nec.co.jp>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---

diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index eb5cd4c3bbfd..7a79fbe9f539 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -509,7 +509,8 @@ static int nfs_lock(struct file *filp, int cmd, struct file_lock *fl)
 		return -EINVAL;
 
 	/* No mandatory locks over NFS */
-	if ((inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID)
+	if ((inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID &&
+	    fl->fl_type != F_UNLCK)
 		return -ENOLCK;
 
 	if (IS_GETLK(cmd))