16bf3d33c6
In rmnet_map_ipv4_dl_csum_trailer(), an illegal checksum subtraction is done, subtracting hdr_csum (in host byte order) from csum_value (in network byte order). Despite being illegal, it generally works, because it turns out the value subtracted is (or should be) always 0, which has the same representation in either byte order. Doing illegal operations is not good form though, so fix this by verifying the IP header checksum early in that function. If its checksum is non-zero, the packet will be bad, so just return an error. This will cause the packet to passed to the IP layer where it can be dropped. Thereafter, there is no need subtract the IP header checksum from the checksum value in the trailer because we know it is zero. Add a comment explaining this. This type of packet error is different from other types, so add a new statistics counter to track this condition. Signed-off-by: Alex Elder <elder@linaro.org> Signed-off-by: David S. Miller <davem@davemloft.net>
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.