[PATCH 4.11 02/36] fs: completely ignore unknown open flags - Greg Kroah-Hartman

From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
	Al Viro <viro@zeniv.linux.org.uk>
Subject: [PATCH 4.11 02/36] fs: completely ignore unknown open flags
Date: Mon, 10 Jul 2017 19:10:29 +0200	[thread overview]
Message-ID: <20170710171047.451236022@linuxfoundation.org> (raw)
In-Reply-To: <20170710171047.340538749@linuxfoundation.org>

4.11-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Christoph Hellwig <hch@lst.de>

commit 629e014bb8349fcf7c1e4df19a842652ece1c945 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/open.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/fs/open.c
+++ b/fs/open.c
@@ -900,6 +900,12 @@ static inline int build_open_flags(int f
 	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
