76f3b97e56c69fc6ebce492a825befd311e57c4d

commit 45e1058b77feade4e36402828bfe3e0d3363177b upstream.
The call to:
ret = simple_write_to_buffer(buf, size, offp, ubuf, size);
will return success if it is able to write even one byte to "buf".
The value of "*offp" controls which byte. This could result in
reading uninitialized data when we do the sscanf() on the next line.
This code is not really desigined to handle partial writes where
*offp is non-zero and the "buf" is preserved and re-used between writes.
Just ban partial writes and replace the simple_write_to_buffer() with
copy_from_user().
Fixes: 578b881ba9
("NTB: Add tool test client")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>
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.
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