From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BA2F9C433E9 for ; Tue, 12 Jan 2021 13:16:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8022D22CAF for ; Tue, 12 Jan 2021 13:16:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726387AbhALNQC (ORCPT ); Tue, 12 Jan 2021 08:16:02 -0500 Received: from mail.kernel.org ([198.145.29.99]:36292 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730094AbhALNP1 (ORCPT ); Tue, 12 Jan 2021 08:15:27 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id D775C22571 for ; Tue, 12 Jan 2021 13:14:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1610457287; bh=It8hwsp3kwp1MvkNdVmaMkspUPQDFXCoPYoDzNp0vNM=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=o4GysrNUvsz6jY7oQOolIbtbyYa48PoscnI2HyAHnhrUQYJT5vZuOsMQWMC/wKIJT e3I2japtQOKmAckkhR5xWb+gmVB3i2ENbhesUp4y4ako8odS8ySND1cRorSaIF2mZT C2C8M100rRnZj8w7As/XK0Sg10+OEyMdmUqt7QYz7b2RaaUuHUonAl9uMSnr6jT0gb vyF2sh4kc+9FYiWNFGJWrhqcX06swnRiJTySHcIWXRkdJbXR/86w6ipzzuxSUf0CvT +Wn6abfsgjIYYXbHZ9IBKrYJHIFyseY1QMGuoTRyPsofWCbD1id2x663Y2/cAMR0ar ZXDwmqhGsmxcQ== Received: by mail-lf1-f42.google.com with SMTP id b26so3273410lff.9 for ; Tue, 12 Jan 2021 05:14:46 -0800 (PST) X-Gm-Message-State: AOAM531LXLp1fVUTa8GXTxWYx8P/71E5pADM0Lxw3vRqQfRfBOvNxz4P IjN6OCV2NqGD7h9g4zEumku2sR4ivbhv1AEJSnkN3Q== X-Google-Smtp-Source: ABdhPJzTTOcnEMQSjDUK8UaKaos3oSZEHBUgqUvMzQpvWIx8CjosYAowjfGBlIlg19oKaPy/y5ODjBk6R+kSNN1Nops= X-Received: by 2002:a19:810:: with SMTP id 16mr2237205lfi.233.1610457285057; Tue, 12 Jan 2021 05:14:45 -0800 (PST) MIME-Version: 1.0 References: <20210112123913.2016804-1-jackmanb@google.com> In-Reply-To: <20210112123913.2016804-1-jackmanb@google.com> From: KP Singh Date: Tue, 12 Jan 2021 14:14:33 +0100 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH bpf-next] bpf: Fix a verifier message for alloc size helper arg To: Brendan Jackman Cc: bpf , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Florent Revest , open list Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Tue, Jan 12, 2021 at 1:39 PM Brendan Jackman wrote: > > The error message here is misleading, the argument will be rejected > unless it is a known constant. > > Signed-off-by: Brendan Jackman > --- > kernel/bpf/verifier.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c > index 17270b8404f1..5534e667bdb1 100644 > --- a/kernel/bpf/verifier.c > +++ b/kernel/bpf/verifier.c > @@ -4319,7 +4319,7 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg, > err = mark_chain_precision(env, regno); > } else if (arg_type_is_alloc_size(arg_type)) { > if (!tnum_is_const(reg->var_off)) { > - verbose(env, "R%d unbounded size, use 'var &= const' or 'if (var < const)'\n", Can you check if: int var = 1000; var += 1; if (var < 2000) // call helper and then using var in the argument works? If so, the existing error message would be correct. > + verbose(env, "R%d is not a known constant'\n", > regno); > return -EACCES; > } > > base-commit: e22d7f05e445165e58feddb4e40cc9c0f94453bc > -- > 2.30.0.284.gd98b1dd5eaa7-goog >