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=-18.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_IN_DEF_DKIM_WL 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 060CAC433DB for ; Fri, 22 Jan 2021 07:25:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D0AC9238D7 for ; Fri, 22 Jan 2021 07:25:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726732AbhAVHYo (ORCPT ); Fri, 22 Jan 2021 02:24:44 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45042 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726741AbhAVHYj (ORCPT ); Fri, 22 Jan 2021 02:24:39 -0500 Received: from mail-oi1-x234.google.com (mail-oi1-x234.google.com [IPv6:2607:f8b0:4864:20::234]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A6F32C0613D6 for ; Thu, 21 Jan 2021 23:23:59 -0800 (PST) Received: by mail-oi1-x234.google.com with SMTP id r189so5076222oih.4 for ; Thu, 21 Jan 2021 23:23:59 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Q2cnartO5VSigxEhPJCDzt4hVZPHOHRMZn656f4qH9k=; b=g5QR4ZtUmJDjkmnh3DTuoxiYrAcmWMYo0up4e1Vv9+gyTD1rA7CO/gPK59cLO7cBmP V5NeWoLxVAsWM8y7enfl2uumiysE2Dcsglkds30d26UasufFkTRUsTQK4Ur3HPLlJqsN 2IZhPV+gi35UDfmHX4ZzgdKCPnHyIPuwcU6+mOlqaCHm9zRmY0m34JVbB7O1evv6Pduk ZC+hp+hAES8ShaMt2OiD52gJmargt/U1oNTk3ApLBs6Vh2KquFfsAKg5PfoBOihh3IJr ial0jb05bA7B2C9LvmADd0iZbmwOplN5Z13hrJdeQKAChl1EupvbkUZi5A2+lcYtuoV8 1t2g== 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=Q2cnartO5VSigxEhPJCDzt4hVZPHOHRMZn656f4qH9k=; b=kIhN1GEXfdDj9z6ahyZ9nJpYECaMczunSW38MHlK9JcV4OM4NFgYJO7JlSSeWChjQl wo64o9GGrYYDl/6DJcBt63EcqW0LMP1trvaYBlk9T+qkw5wZK6w3Np297xy3xp0SgoSz hGD67Kr38Wo3kl0fZYL49kZ/hKGJSP4v47/LeVqhQX+4iDmjMpUrPWezNi7foELYWf2W Xg4LCADmqVPqtlzIIbOeVFzMGaZhiYs5fXSYperapZiZyyhnDUMW0cchEiApwvTdVFVM D6xrnqB59ldHBGZHPRfqiHfmhOB8hz/PdMn0GXECN7QZSBUqjUDV+C4ZHZqA9suGR29V pKYA== X-Gm-Message-State: AOAM533CC8U3eygQtD1m8vs3njPX5nGWRpcwAuzTjgOwnOy41dNsiwBO EnImKCW9gAPEuOJulnHdj0/tsQk6omyxL5LFmSVjIg== X-Google-Smtp-Source: ABdhPJxu/9BWIQb+68tCu13kU7fTlmvXhna/Cn3pz2Yb3dAIRdE06yGxjj3qjHcd2XbwGNlMXlvx2A/E4pCLLUr/J70= X-Received: by 2002:aca:58d6:: with SMTP id m205mr2402924oib.121.1611300238833; Thu, 21 Jan 2021 23:23:58 -0800 (PST) MIME-Version: 1.0 References: <0000000000004c9e3505b96c58eb@google.com> <000000000000d0e9a705b96d4332@google.com> In-Reply-To: <000000000000d0e9a705b96d4332@google.com> From: Marco Elver Date: Fri, 22 Jan 2021 08:23:47 +0100 Message-ID: Subject: Re: UBSAN: array-index-out-of-bounds in decode_data To: syzbot Cc: ajk@comnets.uni-bremen.de, "David S. Miller" , Jakub Kicinski , linux-hams@vger.kernel.org, LKML , Netdev , syzkaller-bugs , Dmitry Vyukov Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 21 Jan 2021 at 19:30, syzbot wrote: > syzbot has found a reproducer for the following issue on: > > HEAD commit: 9791581c Merge tag 'for-5.11-rc4-tag' of git://git.kernel... > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=13cd09a4d00000 > kernel config: https://syzkaller.appspot.com/x/.config?x=39701af622f054a9 > dashboard link: https://syzkaller.appspot.com/bug?extid=70ba6cae2f44c82dcb76 > compiler: gcc (GCC) 10.1.0-syz 20200507 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=133d8030d00000 > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+70ba6cae2f44c82dcb76@syzkaller.appspotmail.com > > ================================================================================ > UBSAN: array-index-out-of-bounds in drivers/net/hamradio/6pack.c:845:16 > index 400 is out of range for type 'unsigned char [400]' > CPU: 1 PID: 8 Comm: kworker/u4:0 Not tainted 5.11.0-rc4-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > Workqueue: events_unbound flush_to_ldisc > Call Trace: > __dump_stack lib/dump_stack.c:79 [inline] > dump_stack+0x107/0x163 lib/dump_stack.c:120 > ubsan_epilogue+0xb/0x5a lib/ubsan.c:148 > __ubsan_handle_out_of_bounds.cold+0x62/0x6c lib/ubsan.c:356 > decode_data.part.0+0x2c8/0x2e0 drivers/net/hamradio/6pack.c:845 It looks like this might be due to a race condition; syzbot had detected a data race in this code a while back, but it seems this was never fixed: https://lore.kernel.org/lkml/000000000000bbb17d05a19540cd@google.com/ > decode_data drivers/net/hamradio/6pack.c:965 [inline] > sixpack_decode drivers/net/hamradio/6pack.c:968 [inline] > sixpack_receive_buf drivers/net/hamradio/6pack.c:458 [inline] > sixpack_receive_buf+0xd8c/0x1320 drivers/net/hamradio/6pack.c:435 > tty_ldisc_receive_buf+0x14a/0x190 drivers/tty/tty_buffer.c:465 > tty_port_default_receive_buf+0x6e/0xa0 drivers/tty/tty_port.c:38 > receive_buf drivers/tty/tty_buffer.c:481 [inline] > flush_to_ldisc+0x20d/0x380 drivers/tty/tty_buffer.c:533 > process_one_work+0x98d/0x15f0 kernel/workqueue.c:2275 > worker_thread+0x64c/0x1120 kernel/workqueue.c:2421 > kthread+0x3b1/0x4a0 kernel/kthread.c:292 > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 > ================================================================================ Thanks, -- Marco