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commit b76abb5157468756163fe7e3431c9fe32cba57ca upstream. If userspace calls this ioctl with fsu_length (the length of the fsuuid.fsu_uuid array) set to zero, ext4 copies the desired uuid length out to userspace. The kernel call returned a result from a valid input, so the return value here should be zero, not EINVAL. While we're at it, fix the copy_to_user call to make it clear that we're only copying out fsu_len. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Catherine Hoang <catherine.hoang@oracle.com> Link: https://lore.kernel.org/r/166811138914.327006.9241306894437166566.stgit@magnolia Signed-off-by: Theodore Ts'o <tytso@mit.edu> Cc: stable@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.