From 9ddd834043f14442b4c40ffc7b86de9e4f5f0ffe Mon Sep 17 00:00:00 2001 From: Al Viro Date: Wed, 27 Apr 2016 01:11:55 -0400 Subject: [PATCH] atomic_open(): fix the handling of create_error [ Upstream commit 10c64cea04d3c75c306b3f990586ffb343b63287 ] * if we have a hashed negative dentry and either CREAT|EXCL on r/o filesystem, or CREAT|TRUNC on r/o filesystem, or CREAT|EXCL with failing may_o_create(), we should fail with EROFS or the error may_o_create() has returned, but not ENOENT. Which is what the current code ends up returning. * if we have CREAT|TRUNC hitting a regular file on a read-only filesystem, we can't fail with EROFS here. At the very least, not until we'd done follow_managed() - we might have a writable file (or a device, for that matter) bound on top of that one. Moreover, the code downstream will see that O_TRUNC and attempt to grab the write access (*after* following possible mount), so if we really should fail with EROFS, it will happen. No need to do that inside atomic_open(). The real logics is much simpler than what the current code is trying to do - if we decided to go for simple lookup, ended up with a negative dentry *and* had create_error set, fail with create_error. No matter whether we'd got that negative dentry from lookup_real() or had found it in dcache. Cc: stable@vger.kernel.org # v3.6+ Acked-by: Miklos Szeredi Signed-off-by: Al Viro Signed-off-by: Sasha Levin --- fs/namei.c | 20 ++++---------------- 1 file changed, 4 insertions(+), 16 deletions(-) diff --git a/fs/namei.c b/fs/namei.c index f3cc848..c7a6eab 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -2839,22 +2839,10 @@ no_open: dentry = lookup_real(dir, dentry, nd->flags); if (IS_ERR(dentry)) return PTR_ERR(dentry); - - if (create_error) { - int open_flag = op->open_flag; - - error = create_error; - if ((open_flag & O_EXCL)) { - if (!dentry->d_inode) - goto out; - } else if (!dentry->d_inode) { - goto out; - } else if ((open_flag & O_TRUNC) && - d_is_reg(dentry)) { - goto out; - } - /* will fail later, go on to get the right error */ - } + } + if (create_error && !dentry->d_inode) { + error = create_error; + goto out; } looked_up: path->dentry = dentry; -- 2.7.4