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=-17.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT,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 9EE88C32753 for ; Wed, 14 Aug 2019 09:12:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6EDA520843 for ; Wed, 14 Aug 2019 09:12:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="jtHvkbb2" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726230AbfHNJMC (ORCPT ); Wed, 14 Aug 2019 05:12:02 -0400 Received: from mail-qt1-f202.google.com ([209.85.160.202]:38554 "EHLO mail-qt1-f202.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725905AbfHNJMC (ORCPT ); Wed, 14 Aug 2019 05:12:02 -0400 Received: by mail-qt1-f202.google.com with SMTP id i13so6870555qtq.5 for ; Wed, 14 Aug 2019 02:12:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:message-id:mime-version:subject:from:to:cc; bh=LZjHGTJXNVoMkySb9EFv36Nm4bNMwzcw1+MXlv5Nd4w=; b=jtHvkbb2v1UBG05Onp9j1UyMjamXkTfR1I6vMGV3KduyFYy2rZfWcb+D3/qjBowJMU f2puYZ/MTBh5haNksLKhMhiS+gOsOXnpETJrygx4M9vNJ59oyiSlpYn2hIAQVxcbF1r4 XjBeZuS7LcITy9Svy6GG5riemxS+hlbnlGLhFVFy6fjr/HiQW2R9lDYbmjsEzd9xD1uU L86pCRSHIm4WWdwwKezsvUUzzJqUH4aSv1WMbk9uz5uC28vKidGd+W+wNsIXEFGjhQcB 1PXnIOLKBUjjREAfZ2GQJd6+cnr2L80eRGWkCo7g/a+OeaUBhQ8y+ddnyRmyqlL4Vezn PZ+Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=LZjHGTJXNVoMkySb9EFv36Nm4bNMwzcw1+MXlv5Nd4w=; b=Aj9WXaLGOsqprpAW9PJgcBb0R6n61wk4ulGkFkdGd21yJyhksggVIlHaasbrqYG3nc fetqrTdswIjnxwEJ/Rzd3C4duBss6ocbrgdYNoQd0hHxL+Gvv7JgBMmLLx+/C9LNvNOX KqTXBak543/A6H3azp/c6uTPG087Kp1KKXreVPmR4t4cQ87YAAFui+OMTWFZJIDLSwB3 NGAmzH3xYjq1SiJFEBIJVJS9fB74leYbldXNDd1dCFaNx3kOC1KIMlyqv/smyu0fxO8P 7Rg0mzel7sLbVMh+L2o5H3MZMshiZYKO+RySIQhgigNzWtQS5Bsj5Hmi5CpsuzNZrIzt c9HQ== X-Gm-Message-State: APjAAAXt37GWXtue/U6h6mbRgLST/l5MJ5lfJbLI/vNbjo1UXcP7ZkVw naF9WkSuOPXxZCIfLP8O1x1dhxL/EOJYRQ== X-Google-Smtp-Source: APXvYqwn0VM404RD1dlK27XddefLMOgiOqmCoW2ralj879+ijr8hUM3zfFgCDdu3kdhCoZgB1FyX7ha3VPhagA== X-Received: by 2002:a0c:f687:: with SMTP id p7mr1696126qvn.160.1565773921113; Wed, 14 Aug 2019 02:12:01 -0700 (PDT) Date: Wed, 14 Aug 2019 02:11:57 -0700 Message-Id: <20190814091157.215108-1-edumazet@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.23.0.rc1.153.gdeed80330f-goog Subject: [PATCH net] net/packet: fix race in tpacket_snd() From: Eric Dumazet To: "David S . Miller" Cc: netdev , Eric Dumazet , Eric Dumazet , syzbot Content-Type: text/plain; charset="UTF-8" Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org packet_sendmsg() checks tx_ring.pg_vec to decide if it must call tpacket_snd(). Problem is that the check is lockless, meaning another thread can issue a concurrent setsockopt(PACKET_TX_RING ) to flip tx_ring.pg_vec back to NULL. Given that tpacket_snd() grabs pg_vec_lock mutex, we can perform the check again to solve the race. syzbot reported : kasan: CONFIG_KASAN_INLINE enabled kasan: GPF could be caused by NULL-ptr deref or user memory access general protection fault: 0000 [#1] PREEMPT SMP KASAN CPU: 1 PID: 11429 Comm: syz-executor394 Not tainted 5.3.0-rc4+ #101 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:packet_lookup_frame+0x8d/0x270 net/packet/af_packet.c:474 Code: c1 ee 03 f7 73 0c 80 3c 0e 00 0f 85 cb 01 00 00 48 8b 0b 89 c0 4c 8d 24 c1 48 b8 00 00 00 00 00 fc ff df 4c 89 e1 48 c1 e9 03 <80> 3c 01 00 0f 85 94 01 00 00 48 8d 7b 10 4d 8b 3c 24 48 b8 00 00 RSP: 0018:ffff88809f82f7b8 EFLAGS: 00010246 RAX: dffffc0000000000 RBX: ffff8880a45c7030 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 1ffff110148b8e06 RDI: ffff8880a45c703c RBP: ffff88809f82f7e8 R08: ffff888087aea200 R09: fffffbfff134ae50 R10: fffffbfff134ae4f R11: ffffffff89a5727f R12: 0000000000000000 R13: 0000000000000001 R14: ffff8880a45c6ac0 R15: 0000000000000000 FS: 00007fa04716f700(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fa04716edb8 CR3: 0000000091eb4000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: packet_current_frame net/packet/af_packet.c:487 [inline] tpacket_snd net/packet/af_packet.c:2667 [inline] packet_sendmsg+0x590/0x6250 net/packet/af_packet.c:2975 sock_sendmsg_nosec net/socket.c:637 [inline] sock_sendmsg+0xd7/0x130 net/socket.c:657 ___sys_sendmsg+0x3e2/0x920 net/socket.c:2311 __sys_sendmmsg+0x1bf/0x4d0 net/socket.c:2413 __do_sys_sendmmsg net/socket.c:2442 [inline] __se_sys_sendmmsg net/socket.c:2439 [inline] __x64_sys_sendmmsg+0x9d/0x100 net/socket.c:2439 do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe Fixes: 69e3c75f4d54 ("net: TX_RING and packet mmap") Signed-off-by: Eric Dumazet Reported-by: syzbot --- net/packet/af_packet.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index 8d54f3047768d2272cbd28a7bcda33df800aa589..e2742b006d255f598fc98953dbb823f615d2bf9a 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -2618,6 +2618,13 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg) mutex_lock(&po->pg_vec_lock); + /* packet_sendmsg() check on tx_ring.pg_vec was lockless, + * we need to confirm it under protection of pg_vec_lock. + */ + if (unlikely(!po->tx_ring.pg_vec)) { + err = -EBUSY; + goto out; + } if (likely(saddr == NULL)) { dev = packet_cached_dev_get(po); proto = po->num; -- 2.23.0.rc1.153.gdeed80330f-goog