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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6BD61C77B75 for ; Mon, 8 May 2023 10:04:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233989AbjEHKER (ORCPT ); Mon, 8 May 2023 06:04:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60440 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233995AbjEHKEQ (ORCPT ); Mon, 8 May 2023 06:04:16 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8604230141 for ; Mon, 8 May 2023 03:04:14 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 11CAA62313 for ; Mon, 8 May 2023 10:04:14 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 25E57C433D2; Mon, 8 May 2023 10:04:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1683540253; bh=Khbh87RWWdQNouIs4MMK/qUhvbE+2WmO8Zfs3QtnoHQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=lhCc+ksXZNqbpL6T16TMaMa6CsT5351MhDSbE7Tfhmt83afhXlcx7uQKndnUGyPSz aRfWQuH1BcfU/oEczALBe9Mx4TAIuiE7vv/zVRT2JF6SFkcTbqcSJRHoDB//dZqOfP AMaSmmZTDrUa/6dGReeVU9CgVex4zXeEciyYHI5c= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Andrii Nakryiko , Alexei Starovoitov , Sasha Levin Subject: [PATCH 6.1 277/611] bpf: take into account liveness when propagating precision Date: Mon, 8 May 2023 11:41:59 +0200 Message-Id: <20230508094431.382425036@linuxfoundation.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230508094421.513073170@linuxfoundation.org> References: <20230508094421.513073170@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Andrii Nakryiko [ Upstream commit 52c2b005a3c18c565fc70cfd0ca49375f301e952 ] When doing state comparison, if old state has register that is not marked as REG_LIVE_READ, then we just skip comparison, regardless what's the state of corresponing register in current state. This is because not REG_LIVE_READ register is irrelevant for further program execution and correctness. All good here. But when we get to precision propagation, after two states were declared equivalent, we don't take into account old register's liveness, and thus attempt to propagate precision for register in current state even if that register in old state was not REG_LIVE_READ anymore. This is bad, because register in current state could be anything at all and this could cause -EFAULT due to internal logic bugs. Fix by taking into account REG_LIVE_READ liveness mark to keep the logic in state comparison in sync with precision propagation. Fixes: a3ce685dd01a ("bpf: fix precision tracking") Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20230309224131.57449-1-andrii@kernel.org Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin --- kernel/bpf/verifier.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 8db2ed564939b..deaeedcdc12d7 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -11908,7 +11908,8 @@ static int propagate_precision(struct bpf_verifier_env *env, state_reg = state->regs; for (i = 0; i < BPF_REG_FP; i++, state_reg++) { if (state_reg->type != SCALAR_VALUE || - !state_reg->precise) + !state_reg->precise || + !(state_reg->live & REG_LIVE_READ)) continue; if (env->log.level & BPF_LOG_LEVEL2) verbose(env, "frame %d: propagating r%d\n", i, fr); @@ -11922,7 +11923,8 @@ static int propagate_precision(struct bpf_verifier_env *env, continue; state_reg = &state->stack[i].spilled_ptr; if (state_reg->type != SCALAR_VALUE || - !state_reg->precise) + !state_reg->precise || + !(state_reg->live & REG_LIVE_READ)) continue; if (env->log.level & BPF_LOG_LEVEL2) verbose(env, "frame %d: propagating fp%d\n", -- 2.39.2