bpf: Ensure line_info.insn_off cannot point to insn with zero code
This patch rejects a line_info if the bpf insn code referred by
line_info.insn_off is 0. F.e. a broken userspace tool might generate
a line_info.insn_off that points to the second 8 bytes of a BPF_LD_IMM64.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index e0e77ff..5c64281 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -4980,6 +4980,14 @@ static int check_btf_line(struct bpf_verifier_env *env,
goto err_free;
}
+ if (!prog->insnsi[linfo[i].insn_off].code) {
+ verbose(env,
+ "Invalid insn code at line_info[%u].insn_off\n",
+ i);
+ err = -EINVAL;
+ goto err_free;
+ }
+
if (!btf_name_by_offset(btf, linfo[i].line_off) ||
!btf_name_by_offset(btf, linfo[i].file_name_off)) {
verbose(env, "Invalid line_info[%u].line_off or .file_name_off\n", i);
