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In commit65c9362859("bpftool: Add struct_ops support") a new type of command named struct_ops has been added. This command requires a kernel with CONFIG_DEBUG_INFO_BTF=y set and for retrieving BTF info in bpftool, the helper get_btf_vmlinux() is used. When running this command on kernel without BTF debug info, this will lead to 'btf_vmlinux' variable being an invalid(error) pointer. And by this, btf_free() causes a segfault when executing 'bpftool struct_ops'. This commit adds pointer validation with IS_ERR not to free invalid pointer, and this will fix the segfault issue. Fixes:65c9362859("bpftool: Add struct_ops support") Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/20200410020612.2930667-1-danieltimlee@gmail.com
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.