The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From ac795161c93699d600db16c1a8cc23a65a1eceaf Mon Sep 17 00:00:00 2001 From: Trond Myklebust trond.myklebust@hammerspace.com Date: Thu, 6 Jan 2022 18:24:02 -0500 Subject: [PATCH] NFSv4: Handle case where the lookup of a directory fails
If the application sets the O_DIRECTORY flag, and tries to open a regular file, nfs_atomic_open() will punt to doing a regular lookup. If the server then returns a regular file, we will happily return a file descriptor with uninitialised open state.
The fix is to return the expected ENOTDIR error in these cases.
Reported-by: Lyu Tao tao.lyu@epfl.ch Fixes: 0dd2b474d0b6 ("nfs: implement i_op->atomic_open()") Signed-off-by: Trond Myklebust trond.myklebust@hammerspace.com Signed-off-by: Anna Schumaker Anna.Schumaker@Netapp.com
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c index 2884138848f4..408c3bb549b1 100644 --- a/fs/nfs/dir.c +++ b/fs/nfs/dir.c @@ -1994,6 +1994,19 @@ int nfs_atomic_open(struct inode *dir, struct dentry *dentry,
no_open: res = nfs_lookup(dir, dentry, lookup_flags); + if (!res) { + inode = d_inode(dentry); + if ((lookup_flags & LOOKUP_DIRECTORY) && inode && + !S_ISDIR(inode->i_mode)) + res = ERR_PTR(-ENOTDIR); + } else if (!IS_ERR(res)) { + inode = d_inode(res); + if ((lookup_flags & LOOKUP_DIRECTORY) && inode && + !S_ISDIR(inode->i_mode)) { + dput(res); + res = ERR_PTR(-ENOTDIR); + } + } if (switched) { d_lookup_done(dentry); if (!res)