Commit 04efe591 authored Jul 19, 2019 by Andrii Nakryiko Committed by Alexei Starovoitov Jul 19, 2019

libbpf: fix SIGSEGV when BTF loading fails, but .BTF.ext exists



In case when BTF loading fails despite sanitization, but BPF object has
.BTF.ext loaded as well, we free and null obj->btf, but not
obj->btf_ext. This leads to an attempt to relocate .BTF.ext later on
during bpf_object__load(), which assumes obj->btf is present. This leads
to SIGSEGV on null pointer access. Fix bug by freeing and nulling
obj->btf_ext as well.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

parent 8d650cde

tools/lib/bpf/libbpf.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -1500,6 +1500,12 @@ static int bpf_object__sanitize_and_load_btf(struct bpf_object *obj)
		BTF_ELF_SEC, err);
		btf__free(obj->btf);
		obj->btf = NULL;
		/* btf_ext can't exist without btf, so free it as well */
		if (obj->btf_ext) {
		btf_ext__free(obj->btf_ext);
		obj->btf_ext = NULL;
		}

		if (bpf_object__is_btf_mandatory(obj))
		return err;
		}