Received: by 10.192.165.156 with SMTP id m28csp78897imm; Tue, 10 Apr 2018 16:51:12 -0700 (PDT) X-Google-Smtp-Source: AIpwx4/2QLPDgyxbIjw8fIUhXjCmLwWHjMryd4Uv4I8/2yjMrwA0svNaOBBk0Buu3InOVXEz1EKD X-Received: by 2002:a17:902:3084:: with SMTP id v4-v6mr2560710plb.262.1523404272648; Tue, 10 Apr 2018 16:51:12 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1523404272; cv=none; d=google.com; s=arc-20160816; b=MlnBnUZ77v1u1iIQrQGJh3JbP2n5BeS9R4wzH+3Qgh61GJTXcTkU5ERFOSCtfasgfF 7WEOJpuf5pqmNwOlCKd/Ul+ls5t+hfvhr8spC1Ut/Eqk0S5WtJjTKDHsgosbDY4/tJQW yEQTB53wGMly5XP2d4y+NFeQOz4TmGMLAYJcnvhFUROsTHwBrFzyMcTZmgqM1ybZzu3g nqNwtHj+L6lsKerfHQMCFKgyCgfZuuJBIMe3FcG879iZp0WUQ3sJ0pRMwaIqyfQl6pgE UU2ojJ5eMPwTw6c6bNmHog/BGhzmFiWMbuAgVSMfL4PkI4A4evUXMn4WkTP7OLF2RMCx 3JIw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:mime-version:user-agent:references :in-reply-to:message-id:date:subject:cc:to:from :arc-authentication-results; bh=sSKvyGEXyBLSxP0giGfELYDR/frN3KSrohHBWnQRAdA=; b=cqC4iVE4B5IAnw15bu11RK0RqQEHq+NRiCMBGsxSaVf6S4J21f4QgFXpN4wTFD+VzJ gMkQsExeaz/1VoFGVo0R7L4hs64BDnROymCw521XMdn/+xtW1o+LSQ6Bf1bYvaRUJ4y7 XOFl7Es4xIZMfZ5fxTJp4xSCBS4HW8kithZuwwyO1H4pXVBRJSHhRPaxaCiDvWB+LTJf piwZOjRZGPF6ncsKl6pgg9pm7QGlpJNoSduveLTP1+XHVSkm3Uz4L5TtUsDu9+MWANCf 4N+l2u2UkyG0Sn3wwByLfk7p+o0mI2/+1GkofLneC60l9tIarNk720INDGkN2qeyicA7 TWrA== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id t2si2464580pgb.209.2018.04.10.16.50.35; Tue, 10 Apr 2018 16:51:12 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752482AbeDJWY3 (ORCPT + 99 others); Tue, 10 Apr 2018 18:24:29 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:36722 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752369AbeDJWYX (ORCPT ); Tue, 10 Apr 2018 18:24:23 -0400 Received: from localhost (LFbn-1-12247-202.w90-92.abo.wanadoo.fr [90.92.61.202]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id 93384CFC; Tue, 10 Apr 2018 22:24:22 +0000 (UTC) From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eric Dumazet , "David S. Miller" Subject: [PATCH 4.16 06/18] pptp: remove a buggy dst release in pptp_connect() Date: Wed, 11 Apr 2018 00:23:41 +0200 Message-Id: <20180410212758.885451569@linuxfoundation.org> X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180410212758.564682823@linuxfoundation.org> References: <20180410212758.564682823@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 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 4.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Upstream commit bfacfb457b36911a10140b8cb3ce76a74883ac5a ] Once dst has been cached in socket via sk_setup_caps(), it is illegal to call ip_rt_put() (or dst_release()), since sk_setup_caps() did not change dst refcount. We can still dereference it since we hold socket lock. Caugth by syzbot : BUG: KASAN: use-after-free in atomic_dec_return include/asm-generic/atomic-instrumented.h:198 [inline] BUG: KASAN: use-after-free in dst_release+0x27/0xa0 net/core/dst.c:185 Write of size 4 at addr ffff8801c54dc040 by task syz-executor4/20088 CPU: 1 PID: 20088 Comm: syz-executor4 Not tainted 4.16.0+ #376 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x1a7/0x27d lib/dump_stack.c:53 print_address_description+0x73/0x250 mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report+0x23c/0x360 mm/kasan/report.c:412 check_memory_region_inline mm/kasan/kasan.c:260 [inline] check_memory_region+0x137/0x190 mm/kasan/kasan.c:267 kasan_check_write+0x14/0x20 mm/kasan/kasan.c:278 atomic_dec_return include/asm-generic/atomic-instrumented.h:198 [inline] dst_release+0x27/0xa0 net/core/dst.c:185 sk_dst_set include/net/sock.h:1812 [inline] sk_dst_reset include/net/sock.h:1824 [inline] sock_setbindtodevice net/core/sock.c:610 [inline] sock_setsockopt+0x431/0x1b20 net/core/sock.c:707 SYSC_setsockopt net/socket.c:1845 [inline] SyS_setsockopt+0x2ff/0x360 net/socket.c:1828 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x4552d9 RSP: 002b:00007f4878126c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000036 RAX: ffffffffffffffda RBX: 00007f48781276d4 RCX: 00000000004552d9 RDX: 0000000000000019 RSI: 0000000000000001 RDI: 0000000000000013 RBP: 000000000072bea0 R08: 0000000000000010 R09: 0000000000000000 R10: 00000000200010c0 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000526 R14: 00000000006fac30 R15: 0000000000000000 Allocated by task 20088: save_stack+0x43/0xd0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 [inline] kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:552 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489 kmem_cache_alloc+0x12e/0x760 mm/slab.c:3542 dst_alloc+0x11f/0x1a0 net/core/dst.c:104 rt_dst_alloc+0xe9/0x540 net/ipv4/route.c:1520 __mkroute_output net/ipv4/route.c:2265 [inline] ip_route_output_key_hash_rcu+0xa49/0x2c60 net/ipv4/route.c:2493 ip_route_output_key_hash+0x20b/0x370 net/ipv4/route.c:2322 __ip_route_output_key include/net/route.h:126 [inline] ip_route_output_flow+0x26/0xa0 net/ipv4/route.c:2577 ip_route_output_ports include/net/route.h:163 [inline] pptp_connect+0xa84/0x1170 drivers/net/ppp/pptp.c:453 SYSC_connect+0x213/0x4a0 net/socket.c:1639 SyS_connect+0x24/0x30 net/socket.c:1620 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x42/0xb7 Freed by task 20082: save_stack+0x43/0xd0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 [inline] __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:520 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:527 __cache_free mm/slab.c:3486 [inline] kmem_cache_free+0x83/0x2a0 mm/slab.c:3744 dst_destroy+0x266/0x380 net/core/dst.c:140 dst_destroy_rcu+0x16/0x20 net/core/dst.c:153 __rcu_reclaim kernel/rcu/rcu.h:178 [inline] rcu_do_batch kernel/rcu/tree.c:2675 [inline] invoke_rcu_callbacks kernel/rcu/tree.c:2930 [inline] __rcu_process_callbacks kernel/rcu/tree.c:2897 [inline] rcu_process_callbacks+0xd6c/0x17b0 kernel/rcu/tree.c:2914 __do_softirq+0x2d7/0xb85 kernel/softirq.c:285 The buggy address belongs to the object at ffff8801c54dc000 which belongs to the cache ip_dst_cache of size 168 The buggy address is located 64 bytes inside of 168-byte region [ffff8801c54dc000, ffff8801c54dc0a8) The buggy address belongs to the page: page:ffffea0007153700 count:1 mapcount:0 mapping:ffff8801c54dc000 index:0x0 flags: 0x2fffc0000000100(slab) raw: 02fffc0000000100 ffff8801c54dc000 0000000000000000 0000000100000010 raw: ffffea0006b34b20 ffffea0006b6c1e0 ffff8801d674a1c0 0000000000000000 page dumped because: kasan: bad access detected Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- drivers/net/ppp/pptp.c | 1 - 1 file changed, 1 deletion(-) --- a/drivers/net/ppp/pptp.c +++ b/drivers/net/ppp/pptp.c @@ -464,7 +464,6 @@ static int pptp_connect(struct socket *s po->chan.mtu = dst_mtu(&rt->dst); if (!po->chan.mtu) po->chan.mtu = PPP_MRU; - ip_rt_put(rt); po->chan.mtu -= PPTP_HEADER_OVERHEAD; po->chan.hdrlen = 2 + sizeof(struct pptp_gre_header);