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commitf858c2b2caupstream. The verifier allows programs to call global functions as long as their argument types match, using BTF to check the function arguments. One of the allowed argument types to such global functions is PTR_TO_CTX; however the check for this fails on BPF_PROG_TYPE_EXT functions because the verifier uses the wrong type to fetch the vmlinux BTF ID for the program context type. This failure is seen when an XDP program is loaded using libxdp (which loads it as BPF_PROG_TYPE_EXT and attaches it to a global XDP type program). Fix the issue by passing in the target program type instead of the BPF_PROG_TYPE_EXT type to bpf_prog_get_ctx() when checking function argument compatibility. The first Fixes tag refers to the latest commit that touched the code in question, while the second one points to the code that first introduced the global function call verification. v2: - Use resolve_prog_type() Fixes:3363bd0cfb("bpf: Extend kfunc with PTR_TO_CTX, PTR_TO_MEM argument support") Fixes:51c39bb1d5("bpf: Introduce function-by-function verification") Reported-by: Simon Sundberg <simon.sundberg@kau.se> Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com> Link: https://lore.kernel.org/r/20220606075253.28422-1-toke@redhat.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> [ backport: open-code missing resolve_prog_type() helper, resolve context diff ] Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com> 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.