57bd08a301
commit 2b405533c2560d7878199c57d95a39151351df72 upstream.
commit 2b74b0a04d3e ("USB: gadget: f_ncm: add bounds checks to ncm_unwrap_ntb()")
adds important bounds checking however it unfortunately also introduces a
bug with respect to section 3.3.1 of the NCM specification.
wDatagramIndex[1] : "Byte index, in little endian, of the second datagram
described by this NDP16. If zero, then this marks the end of the sequence
of datagrams in this NDP16."
wDatagramLength[1]: "Byte length, in little endian, of the second datagram
described by this NDP16. If zero, then this marks the end of the sequence
of datagrams in this NDP16."
wDatagramIndex[1] and wDatagramLength[1] respectively then may be zero but
that does not mean we should throw away the data referenced by
wDatagramIndex[0] and wDatagramLength[0] as is currently the case.
Breaking the loop on (index2 == 0 || dg_len2 == 0) should come at the end
as was previously the case and checks for index2 and dg_len2 should be
removed since zero is valid.
I'm not sure how much testing the above patch received but for me right now
after enumeration ping doesn't work. Reverting the commit restores ping,
scp, etc.
The extra validation associated with wDatagramIndex[0] and
wDatagramLength[0] appears to be valid so, this change removes the incorrect
restriction on wDatagramIndex[1] and wDatagramLength[1] restoring data
processing between host and device.
Fixes: 2b74b0a04d3e ("USB: gadget: f_ncm: add bounds checks to ncm_unwrap_ntb()")
Cc: Ilja Van Sprundel <ivansprundel@ioactive.com>
Cc: Brooke Basile <brookebasile@gmail.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Link: https://lore.kernel.org/r/20200920170158.1217068-1-bryan.odonoghue@linaro.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.