From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yonghong Song Subject: [PATCH bpf-next v4 04/10] bpf: remove never-hit branches in verifier adjust_scalar_min_max_vals Date: Sun, 22 Apr 2018 23:03:57 -0700 Message-ID: <20180423060403.1035526-5-yhs@fb.com> References: <20180423060403.1035526-1-yhs@fb.com> Mime-Version: 1.0 Content-Type: text/plain Cc: To: , , Return-path: Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:47794 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751932AbeDWGEG (ORCPT ); Mon, 23 Apr 2018 02:04:06 -0400 Received: from pps.filterd (m0044012.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w3N5t9Kk011496 for ; Sun, 22 Apr 2018 23:04:06 -0700 Received: from mail.thefacebook.com ([199.201.64.23]) by mx0a-00082601.pphosted.com with ESMTP id 2hh39xrheq-3 (version=TLSv1 cipher=ECDHE-RSA-AES256-SHA bits=256 verify=NOT) for ; Sun, 22 Apr 2018 23:04:05 -0700 In-Reply-To: <20180423060403.1035526-1-yhs@fb.com> Sender: netdev-owner@vger.kernel.org List-ID: In verifier function adjust_scalar_min_max_vals, when src_known is false and the opcode is BPF_LSH/BPF_RSH, early return will happen in the function. So remove the branch in handling BPF_LSH/BPF_RSH when src_known is false. Signed-off-by: Yonghong Song --- kernel/bpf/verifier.c | 11 ++--------- 1 file changed, 2 insertions(+), 9 deletions(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index d00bf53..1bbb43d 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2932,10 +2932,7 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env, dst_reg->umin_value <<= umin_val; dst_reg->umax_value <<= umax_val; } - if (src_known) - dst_reg->var_off = tnum_lshift(dst_reg->var_off, umin_val); - else - dst_reg->var_off = tnum_lshift(tnum_unknown, umin_val); + dst_reg->var_off = tnum_lshift(dst_reg->var_off, umin_val); /* We may learn something more from the var_off */ __update_reg_bounds(dst_reg); break; @@ -2963,11 +2960,7 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env, */ dst_reg->smin_value = S64_MIN; dst_reg->smax_value = S64_MAX; - if (src_known) - dst_reg->var_off = tnum_rshift(dst_reg->var_off, - umin_val); - else - dst_reg->var_off = tnum_rshift(tnum_unknown, umin_val); + dst_reg->var_off = tnum_rshift(dst_reg->var_off, umin_val); dst_reg->umin_value >>= umax_val; dst_reg->umax_value >>= umin_val; /* We may learn something more from the var_off */ -- 2.9.5