From: Christoph Hellwig <hch@lst.de>
Date: Thu, 27 Apr 2017 07:42:25 +0000 (+0200)
Subject: fs: completely ignore unknown open flags
X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=629e014bb8349fcf7c1e4df19a842652ece1c945;p=openwrt%2Fstaging%2Fblogic.git

fs: completely ignore unknown open flags

Currently we just stash anything we got into file->f_flags, and the
report it in fcntl(F_GETFD).  This patch just clears out all unknown
flags so that we don't pass them to the fs or report them.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---

diff --git a/fs/open.c b/fs/open.c
index 949cef29c3bb..7bba2b952f1e 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -900,6 +900,12 @@ static inline int build_open_flags(int flags, umode_t mode, struct open_flags *o
 	int lookup_flags = 0;
 	int acc_mode = ACC_MODE(flags);
 
+	/*
+	 * Clear out all open flags we don't know about so that we don't report
+	 * them in fcntl(F_GETFD) or similar interfaces.
+	 */
+	flags &= VALID_OPEN_FLAGS;
+
 	if (flags & (O_CREAT | __O_TMPFILE))
 		op->mode = (mode & S_IALLUGO) | S_IFREG;
 	else