bpf: Inherit expanded/patched seen count from old aux data

mainline inclusion
from mainline-v5.13-rc7
commit d203b0fd
category: bugfix
bugzilla: NA
CVE: CVE-2021-33624

--------------------------------

Instead of relying on current env->pass_cnt, use the seen count from the
old aux data in adjust_insn_aux_data(), and expand it to the new range of
patched instructions. This change is valid given we always expand 1:n
with n>=1, so what applies to the old/original instruction needs to apply
for the replacement as well.

Not relying on env->pass_cnt is a prerequisite for a later change where we
want to avoid marking an instruction seen when verified under speculative
execution path.
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Reviewed-by: NJohn Fastabend <john.fastabend@gmail.com>
Reviewed-by: NBenedict Schlueter <benedict.schlueter@rub.de>
Reviewed-by: NPiotr Krysiuk <piotras@gmail.com>
Acked-by: NAlexei Starovoitov <ast@kernel.org>

Conflicts:
  kernel/bpf/verifier.c

seen of bpf_insn_aux_data is bool in kernel-4.19.
Signed-off-by: NHe Fengqing <hefengqing@huawei.com>
Reviewed-by: NKuohai Xu <xukuohai@huawei.com>
Reviewed-by: NXiu Jianfeng <xiujianfeng@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

kernel/bpf/verifier.c

@@ -5905,6 +5905,7 @@ static int adjust_insn_aux_data(struct bpf_verifier_env *env, u32 prog_len,
 				u32 off, u32 cnt)
 {
 	struct bpf_insn_aux_data *new_data, *old_data = env->insn_aux_data;
+	bool old_seen = old_data[off].seen;
 	int i;
 
 	if (cnt == 1)
@@ -5916,8 +5917,10 @@ static int adjust_insn_aux_data(struct bpf_verifier_env *env, u32 prog_len,
 	memcpy(new_data, old_data, sizeof(struct bpf_insn_aux_data) * off);
 	memcpy(new_data + off + cnt - 1, old_data + off,
 	       sizeof(struct bpf_insn_aux_data) * (prog_len - off - cnt + 1));
-	for (i = off; i < off + cnt - 1; i++)
-		new_data[i].seen = true;
+	for (i = off; i < off + cnt - 1; i++) {
+		/* Expand insni[off]'s seen count to the patched range. */
+		new_data[i].seen = old_seen;
+	}
 	env->insn_aux_data = new_data;
 	vfree(old_data);
 	return 0;