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

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commit d203b0fd86 upstream

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>
[OP: declare old_data as bool instead of u32 (struct bpf_insn_aux_data.seen
     is bool in 5.4)]
Signed-off-by: Ovidiu Panait <ovidiu.panait@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Daniel Borkmann
2021-08-05 18:53:38 +03:00
committed by Greg Kroah-Hartman
parent a0a9546aae
commit 283d742988
1 changed files with 3 additions and 1 deletions
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4
kernel/bpf/verifier.c
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@@ -8304,6 +8304,7 @@ 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;
bool old_seen = old_data[off].seen;
u32 prog_len;
int i;
@@ -8324,7 +8325,8 @@ 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 = true;
/* 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;