linux-kernel - [PATCH 2/2] fs: reject unknown open flags

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Message-Id: <20170330163327.23920-3-hch@lst.de>
Date:   Thu, 30 Mar 2017 18:33:27 +0200
From:   Christoph Hellwig <hch@....de>
To:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Alexander Viro <viro@...iv.linux.org.uk>
Cc:     linux-api@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, libc-alpha@...rceware.org
Subject: [PATCH 2/2] fs: reject unknown open flags

This way userspace can probe for actually supported flags.

Signed-off-by: Christoph Hellwig <hch@....de>
---
 fs/open.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/open.c b/fs/open.c
index 949cef29c3bb..9106ed7310f0 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -900,6 +900,9 @@ 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);
 
+	if (flags & ~VALID_OPEN_FLAGS)
+		return -EINVAL;
+
 	if (flags & (O_CREAT | __O_TMPFILE))
 		op->mode = (mode & S_IALLUGO) | S_IFREG;
 	else
-- 
2.11.0