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libbpf: Fix strncat bounds error in libbpf_prog_type_by_name 

On compiling samples with this change, one gets an error:

 error: ‘strncat’ specified bound 118 equals destination size
  [-Werror=stringop-truncation]

    strncat(dst, name + section_names[i].len,
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     sizeof(raw_tp_btf_name) - (dst - raw_tp_btf_name));
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

strncat requires the destination to have enough space for the
terminating null byte.

Fixes: f75a697e09 ("libbpf: Auto-detect btf_id of BTF-based raw_tracepoint")
Signed-off-by: KP Singh <kpsingh@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20191023154038.24075-1-kpsingh@chromium.org
This commit is contained in:
KP Singh 2019-10-23 17:40:38 +02:00 committed by Alexei Starovoitov
parent e0e4f8e938
commit 58eeb2289a
1 changed files with 1 additions and 1 deletions
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2
tools/lib/bpf/libbpf.c
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@ -4690,7 +4690,7 @@ int libbpf_prog_type_by_name(const char *name, enum bpf_prog_type *prog_type,
}
/* prepend "btf_trace_" prefix per kernel convention */
strncat(dst, name + section_names[i].len,
sizeof(raw_tp_btf_name) - (dst - raw_tp_btf_name));
sizeof(raw_tp_btf_name) - sizeof("btf_trace_"));
ret = btf__find_by_name(btf, raw_tp_btf_name);
btf__free(btf);
if (ret <= 0) {