Commit 44942b4e authored Jun 27, 2019 by Trond Myklebust

NFSv4: Handle the special Linux file open access mode



According to the open() manpage, Linux reserves the access mode 3
to mean "check for read and write permission on the file and return
a file descriptor that can't be used for reading or writing."

Currently, the NFSv4 code will ask the server to open the file,
and will use an incorrect share access mode of 0. Since it has
an incorrect share access mode, the client later forgets to send
a corresponding close, meaning it can leak stateids on the server.

Fixes: ce4ef7c0 ("NFS: Split out NFS v4 file operations")
Cc: stable@vger.kernel.org # 3.6+
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

parent 1bf85d8c

fs/nfs/inode.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -1100,6 +1100,7 @@ int nfs_open(struct inode inode, struct file filp)
		nfs_fscache_open_file(inode, filp);
		return 0;
		}
		EXPORT_SYMBOL_GPL(nfs_open);

		/*
		* This function is called whenever some part of NFS notices that

fs/nfs/nfs4file.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -49,7 +49,7 @@ nfs4_file_open(struct inode inode, struct file filp)
		return err;

		if ((openflags & O_ACCMODE) == 3)
		openflags--;
		return nfs_open(inode, filp);

		/* We can't create new files here */
		openflags &= ~(O_CREAT\|O_EXCL);

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