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=-0.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no 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 472F1C47253 for ; Thu, 30 Apr 2020 18:17:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2664820836 for ; Thu, 30 Apr 2020 18:17:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="ayuUj7W5" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726524AbgD3SRG (ORCPT ); Thu, 30 Apr 2020 14:17:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40374 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1725844AbgD3SRF (ORCPT ); Thu, 30 Apr 2020 14:17:05 -0400 Received: from mail-qk1-x743.google.com (mail-qk1-x743.google.com [IPv6:2607:f8b0:4864:20::743]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6188EC035494; Thu, 30 Apr 2020 11:17:04 -0700 (PDT) Received: by mail-qk1-x743.google.com with SMTP id n143so6721150qkn.8; Thu, 30 Apr 2020 11:17:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=yZrKhc9dDBRwqB8I37WnRLZepK2tKLx0T5FQSB8wP0w=; b=ayuUj7W5/4QbQ8iSRkEyEbcGsdDQQO1V0TG8CliZJOKEcORyj0P3G2Y3+DsPT+81ir 9Soj9PaMJV2FIDMGadUtObCplfgS6ibiXKC8PsW6LiHVg6406gK8/5DPnkVdotOdRT5V YmcTtwa8AZptBcDOweBesBi6l/uX9V9sHOoVUuxta4kl8avSP3B0yEdETLftruBh70Ma NVWGiCiahHehCXnHvx1mluuOH9l72xGxC5Ft+xtRGpW+iyxKMGiEHMLIOUxiH6D5EnXF 7ezC9jqXqWnRd2tkBrOEVDsT+2izZjOactJ+zCIrGu54Rp5NMM+6IzcyThCTQ1D5vhip jGNA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=yZrKhc9dDBRwqB8I37WnRLZepK2tKLx0T5FQSB8wP0w=; b=PZjSsvFf4PW+wf60BxAFlXrR/U7o17gqP4Y+Ll7RB86Ty4FBwzDPsK324pdF+nxCF7 abjdk3lhi92xeNM4dk0m0c7esYFYYBeRRyBqRhGuZk2zRZdp2+2gtQiKeuwrTMhtj17i OpfCwcFn42MWtNtjqNMmZM4zGj5Ipyo2aZwiBp33S/Vgmb27IqTTY38d3iZtiftCAlrg QS0h2lyTvwKVQ+lJ2QTCOuB/XOs5vnf5fA61gKnp/Zndeg/wEf+gNo9B63QcNZSLHYB0 eVjIOpRUj8AoPRYD4Z6ZyQC92b9KoIh3hF8IA+aR9YXRhnGcIBHpaJcZlNP2qM0GrTiV +gwg== X-Gm-Message-State: AGi0Pub1yDjSR5iNzlmw5RofsnZ3/1iCTQ/g7d9/zV7rV4MQZy8RyM57 HDW95Ik/KpECpJK+0F1+4pUNTOSbRyLClUrfLtM= X-Google-Smtp-Source: APiQypKonPFhwRgU4/UIKRVBFEGHIOnqS8FRKfkMmy0dzmV76hOno2jzYwpMeIHe3A6Gc5nXC3zcCoyki3aBVkHhcuI= X-Received: by 2002:ae9:eb8c:: with SMTP id b134mr4941172qkg.39.1588270623433; Thu, 30 Apr 2020 11:17:03 -0700 (PDT) MIME-Version: 1.0 References: <0000000000006780dc05a47ed632@google.com> <2ae442cb-b6ab-0624-a2a0-0f98a5c217bf@iogearbox.net> In-Reply-To: <2ae442cb-b6ab-0624-a2a0-0f98a5c217bf@iogearbox.net> From: Andrii Nakryiko Date: Thu, 30 Apr 2020 11:16:52 -0700 Message-ID: Subject: Re: KASAN: use-after-free Write in bpf_link_put To: Daniel Borkmann Cc: syzbot , Andrii Nakryiko , Alexei Starovoitov , bpf , john fastabend , Martin Lau , KP Singh , open list , Networking , Song Liu , syzkaller-bugs@googlegroups.com, Yonghong Song Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 30, 2020 at 7:36 AM Daniel Borkmann wrote: > > On 4/30/20 11:39 AM, syzbot wrote: > > Hello, > > > > syzbot found the following crash on: > > > > HEAD commit: 449e14bf bpf: Fix unused variable warning > > git tree: bpf-next > > console output: https://syzkaller.appspot.com/x/log.txt?x=109eb5f8100000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=16d87c420507d444 > > dashboard link: https://syzkaller.appspot.com/bug?extid=39b64425f91b5aab714d > > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > > > > Unfortunately, I don't have any reproducer for this crash yet. > > > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > > Reported-by: syzbot+39b64425f91b5aab714d@syzkaller.appspotmail.com > > > > ================================================================== > > BUG: KASAN: use-after-free in atomic64_dec_and_test include/asm-generic/atomic-instrumented.h:1557 [inline] > > BUG: KASAN: use-after-free in bpf_link_put+0x19/0x1b0 kernel/bpf/syscall.c:2255 > > Write of size 8 at addr ffff8880a7248800 by task syz-executor.0/28011 > > Andrii, ptal, thanks! > yep, looking... > > CPU: 0 PID: 28011 Comm: syz-executor.0 Not tainted 5.7.0-rc2-syzkaller #0 > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > > Call Trace: > > __dump_stack lib/dump_stack.c:77 [inline] > > dump_stack+0x188/0x20d lib/dump_stack.c:118 > > print_address_description.constprop.0.cold+0xd3/0x315 mm/kasan/report.c:382 > > __kasan_report.cold+0x35/0x4d mm/kasan/report.c:511 > > kasan_report+0x33/0x50 mm/kasan/common.c:625 > > check_memory_region_inline mm/kasan/generic.c:187 [inline] > > check_memory_region+0x141/0x190 mm/kasan/generic.c:193 > > atomic64_dec_and_test include/asm-generic/atomic-instrumented.h:1557 [inline] > > bpf_link_put+0x19/0x1b0 kernel/bpf/syscall.c:2255 > > bpf_link_release+0x33/0x40 kernel/bpf/syscall.c:2270 > > __fput+0x33e/0x880 fs/file_table.c:280 > > task_work_run+0xf4/0x1b0 kernel/task_work.c:123 > > tracehook_notify_resume include/linux/tracehook.h:188 [inline] > > exit_to_usermode_loop+0x2fa/0x360 arch/x86/entry/common.c:165 > > prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline] > > syscall_return_slowpath arch/x86/entry/common.c:279 [inline] > > do_syscall_64+0x6b1/0x7d0 arch/x86/entry/common.c:305 > > entry_SYSCALL_64_after_hwframe+0x49/0xb3 > > RIP: 0033:0x7fc891a66469 > > 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:00007fc892156db8 EFLAGS: 00000246 ORIG_RAX: 0000000000000141 > > RAX: fffffffffffffff4 RBX: 000000000042c4e0 RCX: 00007fc891a66469 > > RDX: 0000000000000010 RSI: 0000000020000040 RDI: 000000000000001c > > RBP: 00000000006abf00 R08: 0000000000000000 R09: 0000000000000000 > > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000005 > > R13: 000000000000004f R14: 0000000000415473 R15: 00007fc8921575c0 > > > > Allocated by task 28011: > > save_stack+0x1b/0x40 mm/kasan/common.c:49 > > set_track mm/kasan/common.c:57 [inline] > > __kasan_kmalloc mm/kasan/common.c:495 [inline] > > __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:468 > > kmem_cache_alloc_trace+0x153/0x7d0 mm/slab.c:3551 > > kmalloc include/linux/slab.h:555 [inline] > > kzalloc include/linux/slab.h:669 [inline] > > cgroup_bpf_link_attach+0x13d/0x5b0 kernel/bpf/cgroup.c:894 > > link_create kernel/bpf/syscall.c:3765 [inline] > > __do_sys_bpf+0x238c/0x46d0 kernel/bpf/syscall.c:3987 > > do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295 > > entry_SYSCALL_64_after_hwframe+0x49/0xb3 > > > > Freed by task 28011: > > save_stack+0x1b/0x40 mm/kasan/common.c:49 > > set_track mm/kasan/common.c:57 [inline] > > kasan_set_free_info mm/kasan/common.c:317 [inline] > > __kasan_slab_free+0xf7/0x140 mm/kasan/common.c:456 > > __cache_free mm/slab.c:3426 [inline] > > kfree+0x109/0x2b0 mm/slab.c:3757 > > cgroup_bpf_link_attach+0x2bc/0x5b0 kernel/bpf/cgroup.c:906 > > link_create kernel/bpf/syscall.c:3765 [inline] > > __do_sys_bpf+0x238c/0x46d0 kernel/bpf/syscall.c:3987 > > do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295 > > entry_SYSCALL_64_after_hwframe+0x49/0xb3 > > > > The buggy address belongs to the object at ffff8880a7248800 > > which belongs to the cache kmalloc-128 of size 128 > > The buggy address is located 0 bytes inside of > > 128-byte region [ffff8880a7248800, ffff8880a7248880) > > The buggy address belongs to the page: > > page:ffffea00029c9200 refcount:1 mapcount:0 mapping:00000000a3d4ec31 index:0xffff8880a7248700 > > flags: 0xfffe0000000200(slab) > > raw: 00fffe0000000200 ffffea00024ceac8 ffffea000251d3c8 ffff8880aa000700 > > raw: ffff8880a7248700 ffff8880a7248000 000000010000000f 0000000000000000 > > page dumped because: kasan: bad access detected > > > > Memory state around the buggy address: > > ffff8880a7248700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > ffff8880a7248780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > >> ffff8880a7248800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > ^ > > ffff8880a7248880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > > ffff8880a7248900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > ================================================================== > > > > > > --- > > This bug is generated by a bot. It may contain errors. > > See https://goo.gl/tpsmEJ for more information about syzbot. > > syzbot engineers can be reached at syzkaller@googlegroups.com. > > > > syzbot will keep track of this bug report. See: > > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > > >