strncat()'s third argument is how many bytes will be added *in addition* to already existing bytes in destination. Plus extra zero byte will be added after that. So existing use in test_sockmap has many opportunities to overflow the string and cause memory corruptions. And in this case, GCC complains for a good reason. Fixes: 16962b2404ac ("bpf: sockmap, add selftests") Fixes: 73563aa3d977 ("selftests/bpf: test_sockmap, print additional test options") Fixes: 1ade9abadfca ("bpf: test_sockmap, add options for msg_pop_data() helper") Fixes: 463bac5f1ca7 ("bpf, selftests: Add test for ktls with skb bpf ingress policy") Fixes: e9dd904708c4 ("bpf: add tls support for testing in test_sockmap") Fixes: 753fb2ee0934 ("bpf: sockmap, add msg_peek tests to test_sockmap") Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20201203235440.2302137-2-andrii@kernel.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.
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