From patchwork Mon May 7 16:02:25 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Dumazet X-Patchwork-Id: 909841 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=google.com header.i=@google.com header.b="u1ezwjE4"; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 40fnSp2MZtz9s34 for ; Tue, 8 May 2018 02:02:34 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752624AbeEGQCc (ORCPT ); Mon, 7 May 2018 12:02:32 -0400 Received: from mail-wr0-f195.google.com ([209.85.128.195]:40428 "EHLO mail-wr0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752360AbeEGQCa (ORCPT ); Mon, 7 May 2018 12:02:30 -0400 Received: by mail-wr0-f195.google.com with SMTP id v60-v6so29295936wrc.7 for ; Mon, 07 May 2018 09:02:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=6NVhUpRVgHhRrryvwaUpKBxf1TpqVAEngjGSgsrYhDM=; b=u1ezwjE4asHQT7XRWogFSvevWnRWbJ9o7WBQfxCV0cNuyKwbNs63VT58F7wcaSxuqC crC7KtLJdgl3/jH401zbb9/Xc93TZAoF7YgaxqHocHG625395ndTTE93TuUsaKW2Cy8q tCzEqBjgsizpGorR4Wd7ynDkEsqJUB1wShC2q9U8jsEIyNZ7FV5n/rhJeDp5fSRBJMOt lOL4VZFLmF6R5AEu143dwZ/F2TlwTVfCMr3dyukAEHc4fcG2SwghzMy2XQzkVM4WOno/ rjdC2YtahjjR7LxgO6SJtciowBn2t/wdGT8EG33GL2se6uMlpenLv/imKh5nj2BXyjmf Puug== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=6NVhUpRVgHhRrryvwaUpKBxf1TpqVAEngjGSgsrYhDM=; b=cM/hR3TH3eLkN+AfmgnLwm/8Q1cszaM3KvE48xaySjCjUZQ7cCmZQFvE4CMRjTuley l3n7FebgGGxE1LGkLEgjfykewM4oz3+DATeAIRi8u2v4uTTgqsWqqQVhqZecBi6DANhg VTB4SZY759igebe0++zOvBsiMhYf2Qx7UDLr0TT7DNvd663yzlcUXSq1lnid2uOQDJN5 T5/8FgNZChk+cwW10FydtIsczmUpV62/4edtfKCbK8cP0eOjg49zKYZ7x0gDiKjHmply 7tVKZaD4sjAtwT9RVsedtAJ+QlwXytcQOQTFq8QXM89vYMzwZ8U31MTtdPQOnNwz8jgZ FlPQ== X-Gm-Message-State: ALQs6tB2ZoUjmHQKf2EVdoOnsVLWPz/lG+rBKy170v2cWKgxcjektasd QqAt2GahoQhbux6WSjLTJSffpg== X-Google-Smtp-Source: AB8JxZruF+5JachnG0EcJE5XU9bsMa1nH9H7on50BxQIAs7PqAeD2mP8pflXqk52Bsn9oYY3/MxuVA== X-Received: by 2002:adf:c753:: with SMTP id b19-v6mr28780963wrh.65.1525708949301; Mon, 07 May 2018 09:02:29 -0700 (PDT) Received: from localhost ([2620:15c:2c4:201:f5a:7eca:440a:3ead]) by smtp.gmail.com with ESMTPSA id d12-v6sm25487753wrg.2.2018.05.07.09.02.27 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 07 May 2018 09:02:28 -0700 (PDT) From: Eric Dumazet To: "David S . Miller" Cc: netdev , Eric Dumazet , Eric Dumazet Subject: [PATCH net] llc: better deal with too small mtu Date: Mon, 7 May 2018 09:02:25 -0700 Message-Id: <20180507160225.237901-1-edumazet@google.com> X-Mailer: git-send-email 2.17.0.441.gb46fe60e1d-goog Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org syzbot loves to set very small mtu on devices, since it brings joy. We must make llc_ui_sendmsg() fool proof. usercopy: Kernel memory overwrite attempt detected to wrapped address (offset 0, size 18446612139802320068)! kernel BUG at mm/usercopy.c:100! invalid opcode: 0000 [#1] SMP KASAN Dumping ftrace buffer: (ftrace buffer empty) Modules linked in: CPU: 0 PID: 17464 Comm: syz-executor1 Not tainted 4.17.0-rc3+ #36 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:usercopy_abort+0xbb/0xbd mm/usercopy.c:88 RSP: 0018:ffff8801868bf800 EFLAGS: 00010282 RAX: 000000000000006c RBX: ffffffff87d2fb00 RCX: 0000000000000000 RDX: 000000000000006c RSI: ffffffff81610731 RDI: ffffed0030d17ef6 RBP: ffff8801868bf858 R08: ffff88018daa4200 R09: ffffed003b5c4fb0 R10: ffffed003b5c4fb0 R11: ffff8801dae27d87 R12: ffffffff87d2f8e0 R13: ffffffff87d2f7a0 R14: ffffffff87d2f7a0 R15: ffffffff87d2f7a0 FS: 00007f56a14ac700(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b2bc21000 CR3: 00000001abeb1000 CR4: 00000000001426f0 DR0: 0000000020000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000030602 Call Trace: check_bogus_address mm/usercopy.c:153 [inline] __check_object_size+0x5d9/0x5d9 mm/usercopy.c:256 check_object_size include/linux/thread_info.h:108 [inline] check_copy_size include/linux/thread_info.h:139 [inline] copy_from_iter_full include/linux/uio.h:121 [inline] memcpy_from_msg include/linux/skbuff.h:3305 [inline] llc_ui_sendmsg+0x4b1/0x1530 net/llc/af_llc.c:941 sock_sendmsg_nosec net/socket.c:629 [inline] sock_sendmsg+0xd5/0x120 net/socket.c:639 __sys_sendto+0x3d7/0x670 net/socket.c:1789 __do_sys_sendto net/socket.c:1801 [inline] __se_sys_sendto net/socket.c:1797 [inline] __x64_sys_sendto+0xe1/0x1a0 net/socket.c:1797 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x455979 RSP: 002b:00007f56a14abc68 EFLAGS: 00000246 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 00007f56a14ac6d4 RCX: 0000000000455979 RDX: 0000000000000000 RSI: 0000000020000000 RDI: 0000000000000018 RBP: 000000000072bea0 R08: 00000000200012c0 R09: 0000000000000010 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000548 R14: 00000000006fbf60 R15: 0000000000000000 Code: 55 c0 e8 c0 55 bb ff ff 75 c8 48 8b 55 c0 4d 89 f9 ff 75 d0 4d 89 e8 48 89 d9 4c 89 e6 41 56 48 c7 c7 80 fa d2 87 e8 a0 0b a3 ff <0f> 0b e8 95 55 bb ff e8 c0 a8 f7 ff 8b 95 14 ff ff ff 4d 89 e8 RIP: usercopy_abort+0xbb/0xbd mm/usercopy.c:88 RSP: ffff8801868bf800 Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Eric Dumazet Reported-by: syzbot --- net/llc/af_llc.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/llc/af_llc.c b/net/llc/af_llc.c index cb80ebb38311e7db1e91881cdec59bc33724d856..1beeea9549fa6ec1f7b0e5f9af8ff3250a316f59 100644 --- a/net/llc/af_llc.c +++ b/net/llc/af_llc.c @@ -930,6 +930,9 @@ static int llc_ui_sendmsg(struct socket *sock, struct msghdr *msg, size_t len) if (size > llc->dev->mtu) size = llc->dev->mtu; copied = size - hdrlen; + rc = -EINVAL; + if (copied < 0) + goto release; release_sock(sk); skb = sock_alloc_send_skb(sk, size, noblock, &rc); lock_sock(sk);