Commit 58eeb228 authored Oct 23, 2019 by KP Singh Committed by Alexei Starovoitov Oct 23, 2019

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: f75a697e ("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

parent e0e4f8e9

tools/lib/bpf/libbpf.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -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) {

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