[PATCH 4.4 02/57] fs: completely ignore unknown open flags

From: Greg Kroah-Hartman
Date: Thu Jul 13 2017 - 11:54:41 EST


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

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

From: Christoph Hellwig <hch@xxxxxx>

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@xxxxxx>
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

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

--- a/fs/open.c
+++ b/fs/open.c
@@ -885,6 +885,12 @@ static inline int build_open_flags(int f
int lookup_flags = 0;
int acc_mode;

+ /*
+ * 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