From: Goldwyn Rodrigues <rgoldwyn@suse.de>
To: linux-fsdevel@vger.kernel.org
Cc: amir73il@gmail.com, zohar@linux.ibm.com,
syzbot+ae82084b07d0297e566b@syzkaller.appspotmail.com,
syzkaller-bugs@googlegroups.com, linux-integrity@vger.kernel.org,
linux-unionfs@vger.kernel.org, dvyukov@google.com
Subject: [PATCH] fs: Evaluate O_WRONLY | O_RDWR to O_RDWR
Date: Thu, 13 Dec 2018 05:57:17 -0600 [thread overview]
Message-ID: <20181213115717.p7ncktng2ihxw5md@merlin> (raw)
A user can open(O_WRONLY | O_RDWR) and the options are valid.
However, OPEN_FMODE() evaluates both FMODE_READ and FMODE_WRITE,
as negative. We also need to protect the lower layers from this
anomaly.
Solve it by dropping O_WRONLY, so O_RDWR takes precedence.
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reported-by: syzbot+ae82084b07d0297e566b@syzkaller.appspotmail.com
Fixes: a408e4a86b36 ("ima: open a new file instance if no read permissions")
---
fs/open.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/fs/open.c b/fs/open.c
index 0285ce7dbd51..3d0a21600fa3 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -924,7 +924,12 @@ EXPORT_SYMBOL(open_with_fake_path);
static inline int build_open_flags(int flags, umode_t mode, struct open_flags *op)
{
int lookup_flags = 0;
- int acc_mode = ACC_MODE(flags);
+ int acc_mode;
+
+ if ((flags & (O_RDWR | O_WRONLY)) == (O_RDWR | O_WRONLY))
+ flags &= ~O_WRONLY;
+
+ acc_mode = ACC_MODE(flags);
/*
* Clear out all open flags we don't know about so that we don't report
--
2.16.4
next reply other threads:[~2018-12-13 11:57 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-13 11:57 Goldwyn Rodrigues [this message]
2018-12-13 12:10 ` [PATCH] fs: Evaluate O_WRONLY | O_RDWR to O_RDWR Al Viro
2018-12-13 12:16 ` Amir Goldstein
2018-12-13 12:16 ` Dmitry Vyukov
2018-12-13 12:34 ` Al Viro
2018-12-13 14:05 ` Goldwyn Rodrigues
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