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

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: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Reviewed-by: Benedict Schlueter <benedict.schlueter@rub.de>
Reviewed-by: Piotr Krysiuk <piotras@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 94ba516..f93c7be 100644 (file)
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -11366,6 +11366,7 @@ static int adjust_insn_aux_data(struct bpf_verifier_env *env,
 {
        struct bpf_insn_aux_data *new_data, *old_data = env->insn_aux_data;
        struct bpf_insn *insn = new_prog->insnsi;
+       u32 old_seen = old_data[off].seen;
        u32 prog_len;
        int i;
 
@@ -11386,7 +11387,8 @@ static int adjust_insn_aux_data(struct bpf_verifier_env *env,
        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 = env->pass_cnt;
+               /* Expand insni[off]'s seen count to the patched range. */
+               new_data[i].seen = old_seen;
                new_data[i].zext_dst = insn_has_def32(env, insn + i);
        }
        env->insn_aux_data = new_data;