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=-9.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 2C94BC31E45 for ; Thu, 13 Jun 2019 16:49:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 056072082C for ; Thu, 13 Jun 2019 16:49:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1560444595; bh=5cqCVW7bg2NGvf9UX0zevFyvRJ4mcz8fy35iiQspRS4=; h=From:To:CC:Subject:Date:In-Reply-To:References:List-ID:From; b=PXwYVd87QWT7zWRkXoZRSwZ5JCaBuznOErX9PdfTy627JWHS5Ozq6vWXMtjblgQnt qoFlpOFr0b8dY8nOHT+mwIDxSgsk7q4FDcnqwUU5fVopVc84hwiwVQRAO+AV6Yu2uZ LqXCsQ3i56Mv88TCOGvJxpf2FCOyUmpei5Tafdus= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727685AbfFMQty convert rfc822-to-8bit (ORCPT ); Thu, 13 Jun 2019 12:49:54 -0400 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:54384 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726582AbfFMEUS (ORCPT ); Thu, 13 Jun 2019 00:20:18 -0400 Received: from pps.filterd (m0044010.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x5D4KFhS011073 for ; Wed, 12 Jun 2019 21:20:17 -0700 Received: from maileast.thefacebook.com ([163.114.130.16]) by mx0a-00082601.pphosted.com with ESMTP id 2t365k1s9w-5 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Wed, 12 Jun 2019 21:20:17 -0700 Received: from mx-out.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:83::7) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1713.5; Wed, 12 Jun 2019 21:20:15 -0700 Received: by devbig007.ftw2.facebook.com (Postfix, from userid 572438) id 85C37760CD6; Wed, 12 Jun 2019 21:20:13 -0700 (PDT) Smtp-Origin-Hostprefix: devbig From: Alexei Starovoitov Smtp-Origin-Hostname: devbig007.ftw2.facebook.com To: CC: , , , , , , , , Smtp-Origin-Cluster: ftw2c04 Subject: [PATCH bpf-next 5/9] bpf: fix callees pruning callers Date: Wed, 12 Jun 2019 21:19:59 -0700 Message-ID: <20190613042003.3791852-6-ast@kernel.org> X-Mailer: git-send-email 2.20.0 In-Reply-To: <20190613042003.3791852-1-ast@kernel.org> References: <20190613042003.3791852-1-ast@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT X-FB-Internal: Safe Content-Type: text/plain X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-06-13_02:,, signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 priorityscore=1501 malwarescore=0 suspectscore=1 phishscore=0 bulkscore=0 spamscore=0 clxscore=1034 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=322 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1906130034 X-FB-Internal: deliver Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org The commit 7640ead93924 partially resolved the issue of callees incorrectly pruning the callers. With introduction of bounded loops and jmps_processed heuristic single verifier state may contain multiple branches and calls. It's possible that new verifier state (for future pruning) will be allocated inside callee. Then callee will exit (still within the same verifier state). It will go back to the caller and there R6-R9 registers will be read and will trigger mark_reg_read. But the reg->live for all frames but the top frame is not set to LIVE_NONE. Hence mark_reg_read will fail to propagate liveness into parent and future walking will incorrectly conclude that the states are equivalent because LIVE_READ is not set. In other words the rule for parent/live should be: whenever register parentage chain is set the reg->live should be set to LIVE_NONE. is_state_visited logic already follows this rule for spilled registers. Fixes: 7640ead93924 ("bpf: verifier: make sure callees don't prune with caller differences") Fixes: f4d7e40a5b71 ("bpf: introduce function calls (verification)") Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 55d5ab4ab83e..ef2b69b7bc01 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -6835,17 +6835,18 @@ static int is_state_visited(struct bpf_verifier_env *env, int insn_idx) * the state of the call instruction (with WRITTEN set), and r0 comes * from callee with its full parentage chain, anyway. */ - for (j = 0; j <= cur->curframe; j++) - for (i = j < cur->curframe ? BPF_REG_6 : 0; i < BPF_REG_FP; i++) - cur->frame[j]->regs[i].parent = &new->frame[j]->regs[i]; /* clear write marks in current state: the writes we did are not writes * our child did, so they don't screen off its reads from us. * (There are no read marks in current state, because reads always mark * their parent and current state never has children yet. Only * explored_states can get read marks.) */ - for (i = 0; i < BPF_REG_FP; i++) - cur->frame[cur->curframe]->regs[i].live = REG_LIVE_NONE; + for (j = 0; j <= cur->curframe; j++) { + for (i = j < cur->curframe ? BPF_REG_6 : 0; i < BPF_REG_FP; i++) + cur->frame[j]->regs[i].parent = &new->frame[j]->regs[i]; + for (i = 0; i < BPF_REG_FP; i++) + cur->frame[j]->regs[i].live = REG_LIVE_NONE; + } /* all stack frames are accessible from callee, clear them all */ for (j = 0; j <= cur->curframe; j++) { -- 2.20.0