1fe4850b34
The bpf_fib_lookup() helper does not only look up the fib (ie. route) but it also looks up the neigh. Before returning the neigh, the helper does not check for NUD_VALID. When a neigh state (neigh->nud_state) is in NUD_FAILED, its dmac (neigh->ha) could be all zeros. The helper still returns SUCCESS instead of NO_NEIGH in this case. Because of the SUCCESS return value, the bpf prog directly uses the returned dmac and ends up filling all zero in the eth header. This patch checks for NUD_VALID and returns NO_NEIGH if the neigh is not valid. Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20230217004150.2980689-3-martin.lau@linux.dev
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.