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 66F3CC4167B for ; Mon, 19 Dec 2022 19:14:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231631AbiLSTN5 (ORCPT ); Mon, 19 Dec 2022 14:13:57 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39158 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232482AbiLSTNu (ORCPT ); Mon, 19 Dec 2022 14:13:50 -0500 Received: from mail-pj1-x104a.google.com (mail-pj1-x104a.google.com [IPv6:2607:f8b0:4864:20::104a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 01CFFFD2F for ; Mon, 19 Dec 2022 11:13:49 -0800 (PST) Received: by mail-pj1-x104a.google.com with SMTP id md9-20020a17090b23c900b00218fa3308a9so3940531pjb.8 for ; Mon, 19 Dec 2022 11:13:48 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=9waIoLPfjEIXBT2UAgIFxPvrXTrym213d5FFzQJSSbs=; b=M3Od+rSNpjlUOwidJc2O11k+GNrLWsIR2qpryFM21xIt5ShhYhCW7xh8Xomqib4eXq WDTuo7/pyrpuoDqomVFxF2WEhngdHwxX3g1uEakDRVwhkTMrLSBc3vGsMOBRPY6DntCE BDZSReS3rk/uUG8N/+PFHdLh5xeL6VRz+nSgGS+WBHVnjRoweUNGMYxgbuPXntOr0c+7 6i9b04BLXV5JahofPQCs7JNsoxM1myt+L1ccaj4uXe7nl7HjIAQJ4/W7CobW8jC5CHaH gctgE2GRrzdI1dU+QteWniGZzBwUH8SH9p8Hlj/clDRm4YsYGVUobPlzl7iaOHPgl64Y Fn5A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=9waIoLPfjEIXBT2UAgIFxPvrXTrym213d5FFzQJSSbs=; b=Vu6r3Lf1b2SAVFM8B5BFoG5sd0+GfbS/aFKInxYmZjBX6mxEiiCHnYzUDNt8p+am82 xufWscXNW2D/RmzGmdhkvZz2iQ2XEtV0rDDnK1/V420NC7HU6C29cBwGu1qO7iiXLn5p ILSjjPkEueJ5/U6q0iiWGUQgdVxPqJvH2o8lR+UI1M/brxm22yW8Oyp1O4tiD/xFRVrG B8qnPuv6x5KIGopNYXHvyATbgV+5xDhUVbL2a02+c9lpRb5u9lPsJXn9kIeYKGaTULOa AF4dlxfGJ6BTEO1AVRXFFxMtX6OZl1v5rIdRMrxUc0er2+6rsjz5zzqufvZUhguA17xv CZPA== X-Gm-Message-State: ANoB5plmoSSeFEZGT46ZBxB9bRVX3ZJOLDaPVu7+2Tg6BU4c55V5ADmd cXtVnyTObAMR2n5fQ1TzdnijFhc= X-Google-Smtp-Source: AA0mqf6bJkWslD9a7BOtBa7Tvdb7O06LkIsPilcLEW0XHE1E8JsnY+2z0R+erJyqdu/byOXde33yGyw= X-Received: from sdf.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5935]) (user=sdf job=sendgmr) by 2002:a17:902:6804:b0:189:907c:8380 with SMTP id h4-20020a170902680400b00189907c8380mr50843675plk.104.1671477228478; Mon, 19 Dec 2022 11:13:48 -0800 (PST) Date: Mon, 19 Dec 2022 11:13:46 -0800 In-Reply-To: Mime-Version: 1.0 References: Message-ID: Subject: Re: WARNING in __mark_chain_precision From: sdf@google.com To: Hao Sun , Andrii Nakryiko Cc: bpf , Alexei Starovoitov , Daniel Borkmann , John Fastabend , Martin KaFai Lau , Song Liu , Yonghong Song , KP Singh , Hao Luo , Jiri Olsa , David Miller , Jakub Kicinski , Jesper Dangaard Brouer , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8"; format=flowed; delsp=yes Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/19, Hao Sun wrote: > Hi, > The following backtracking bug can be triggered on the latest bpf-next and > Linux 6.1 with the C prog provided. I don't have enough knowledge about > this part in the verifier, don't know how to fix this. Maybe something related to commit be2ef8161572 ("bpf: allow precision tracking for programs with subprogs") and/or the related ones? > This can be reproduced on: > HEAD commit: 0e43662e61f2 tools/resolve_btfids: Use pkg-config to locate > libelf > git tree: bpf-next > console log: https://pastebin.com/raw/45hZ7iqm > kernel config: https://pastebin.com/raw/0pu1CHRm > C reproducer: https://pastebin.com/raw/tqsiezvT > func#0 @0 > 0: R1=ctx(off=0,imm=0) R10=fp0 > 0: (18) r2 = 0x8000000000000 ; R2_w=2251799813685248 > 2: (18) r6 = 0xffff888027358000 ; > R6_w=map_ptr(off=0,ks=3032,vs=3664,imm=0) > 4: (18) r7 = 0xffff88802735a000 ; > R7_w=map_ptr(off=0,ks=156,vs=2624,imm=0) > 6: (18) r8 = 0xffff88802735e000 ; > R8_w=map_ptr(off=0,ks=2396,vs=76,imm=0) > 8: (18) r9 = 0x8e9700000000 ; R9_w=156779191205888 > 10: (36) if w9 >= 0xffffffe3 goto pc+1 > last_idx 10 first_idx 0 > regs=200 stack=0 before 8: (18) r9 = 0x8e9700000000 > 11: R9_w=156779191205888 > 11: (85) call #0 > 12: (cc) w2 s>>= w7 > last_idx 12 first_idx 12 > parent didn't have regs=4 stack=0 marks: R1=ctx(off=0,imm=0) > R2_rw=P2251799813685248 R6_w=map_ptr(off=0,ks=3032,vs=3664,imm=0) > R7_rw=map_ptr(off=0,ks=156,vs=2624,imm=0) > R8_w=map_ptr(off=0,ks=2396,vs=76,imm=0) R9_w=156779191205888 R10=fp0 > last_idx 11 first_idx 0 > regs=4 stack=0 before 11: (85) call #0 > BUG regs 4 > processed 8 insns (limit 1000000) max_states_per_insn 0 total_states 1 > peak_states 1 mark_read 1 > ------------[ cut here ]------------ > verifier backtracking bug > WARNING: CPU: 6 PID: 8646 at kernel/bpf/verifier.c:2756 backtrack_insn > kernel/bpf/verifier.c:2756 [inline] > WARNING: CPU: 6 PID: 8646 at kernel/bpf/verifier.c:2756 > __mark_chain_precision+0x1baf/0x1d70 kernel/bpf/verifier.c:3065 > Modules linked in: > CPU: 6 PID: 8646 Comm: a.out Not tainted 6.1.0-09634-g0e43662e61f2 #146 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Arch Linux > 1.16.1-1-1 04/01/2014 > RIP: 0010:backtrack_insn kernel/bpf/verifier.c:2756 [inline] > RIP: 0010:__mark_chain_precision+0x1baf/0x1d70 kernel/bpf/verifier.c:3065 > Code: 0d 31 ff 89 de e8 91 ec ed ff 84 db 0f 85 ef fe ff ff e8 b4 f0 > ed ff 48 c7 c7 e0 8f 53 8a c6 05 28 71 ab 0d 01 e8 83 b3 1e 08 <0f> 0b > e9 50 f8 ff ff 48 8b 74 24 38 48 c7 c7 80 d0 63 8d e8 49 46 > RSP: 0018:ffffc9001463f1a0 EFLAGS: 00010282 > RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 > RDX: ffff888020470000 RSI: ffffffff816662c0 RDI: fffff520028c7e26 > RBP: 0000000000000004 R08: 0000000000000005 R09: 0000000000000000 > R10: 0000000080000000 R11: 0000000000000000 R12: 0000000000000020 > R13: dffffc0000000000 R14: 000000000000000b R15: ffff88802be74000 > FS: 00007fd3daeb8440(0000) GS:ffff888063980000(0000) > knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000000020000240 CR3: 0000000017394000 CR4: 0000000000750ee0 > PKRU: 55555554 > Call Trace: > > mark_chain_precision kernel/bpf/verifier.c:3165 [inline] > adjust_reg_min_max_vals+0x981/0x58d0 kernel/bpf/verifier.c:10715 > check_alu_op+0x380/0x1820 kernel/bpf/verifier.c:10928 > do_check kernel/bpf/verifier.c:13821 [inline] > do_check_common+0x1c3b/0xe520 kernel/bpf/verifier.c:16289 > do_check_main kernel/bpf/verifier.c:16352 [inline] > bpf_check+0x83b4/0xb310 kernel/bpf/verifier.c:16936 > bpf_prog_load+0xf7a/0x21a0 kernel/bpf/syscall.c:2619 > __sys_bpf+0xf03/0x5840 kernel/bpf/syscall.c:4979 > __do_sys_bpf kernel/bpf/syscall.c:5083 [inline] > __se_sys_bpf kernel/bpf/syscall.c:5081 [inline] > __x64_sys_bpf+0x78/0xc0 kernel/bpf/syscall.c:5081 > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80 > entry_SYSCALL_64_after_hwframe+0x63/0xcd > RIP: 0033:0x7fd3da8e4469 > Code: 00 f3 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 > 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d > 01 f0 ff ff 73 01 c3 48 8b 0d ff 49 2b 00 f7 d8 64 89 01 48 > RSP: 002b:00007fff090c1a78 EFLAGS: 00000246 ORIG_RAX: 0000000000000141 > RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fd3da8e4469 > RDX: 0000000000000080 RSI: 0000000020000840 RDI: 0000000000000005 > RBP: 00007fff090c2a90 R08: 00007fd3da92e160 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 0000561aefc006c0 > R13: 00007fff090c2b70 R14: 0000000000000000 R15: 0000000000000000 >