From mboxrd@z Thu Jan 1 00:00:00 1970 From: syzbot Subject: Re: KMSAN: uninit-value in sit_tunnel_xmit Date: Fri, 10 Aug 2018 14:30:02 -0700 Message-ID: <00000000000053c91f05731b72b8@google.com> References: <00000000000082e3a90571fadb4c@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8"; format=flowed; delsp=yes To: davem@davemloft.net, kuznet@ms2.inr.ac.ru, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, syzkaller-bugs@googlegroups.com, yoshfuji@linux-ipv6.org Return-path: In-Reply-To: <00000000000082e3a90571fadb4c@google.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org syzbot has found a reproducer for the following crash on: HEAD commit: 0cc51dc9a291 kmsan: instrument get_user() and put_user() p.. git tree: https://github.com/google/kmsan.git/master console output: https://syzkaller.appspot.com/x/log.txt?x=14973622400000 kernel config: https://syzkaller.appspot.com/x/.config?x=3618361797c180a3 dashboard link: https://syzkaller.appspot.com/bug?extid=782ee96f9147673d8822 compiler: clang version 8.0.0 (trunk 339414) syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=10fd6e30400000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17a2aee2400000 IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+782ee96f9147673d8822@syzkaller.appspotmail.com IPv6: ADDRCONF(NETDEV_UP): veth1: link is not ready IPv6: ADDRCONF(NETDEV_CHANGE): veth1: link becomes ready IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready 8021q: adding VLAN 0 to HW filter on device team0 ================================================================== BUG: KMSAN: uninit-value in __ipv6_prefix_equal64_half include/net/ipv6.h:515 [inline] BUG: KMSAN: uninit-value in ipv6_prefix_equal include/net/ipv6.h:532 [inline] BUG: KMSAN: uninit-value in check_6rd net/ipv6/sit.c:771 [inline] BUG: KMSAN: uninit-value in try_6rd net/ipv6/sit.c:805 [inline] BUG: KMSAN: uninit-value in ipip6_tunnel_xmit net/ipv6/sit.c:865 [inline] BUG: KMSAN: uninit-value in sit_tunnel_xmit+0x18c0/0x3640 net/ipv6/sit.c:1029 CPU: 0 PID: 4467 Comm: syz-executor896 Not tainted 4.18.0-rc8+ #33 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+0x17c/0x1c0 lib/dump_stack.c:113 kmsan_report+0x188/0x2a0 mm/kmsan/kmsan.c:982 __msan_warning+0x70/0xc0 mm/kmsan/kmsan_instr.c:645 __ipv6_prefix_equal64_half include/net/ipv6.h:515 [inline] ipv6_prefix_equal include/net/ipv6.h:532 [inline] check_6rd net/ipv6/sit.c:771 [inline] try_6rd net/ipv6/sit.c:805 [inline] ipip6_tunnel_xmit net/ipv6/sit.c:865 [inline] sit_tunnel_xmit+0x18c0/0x3640 net/ipv6/sit.c:1029 __netdev_start_xmit include/linux/netdevice.h:4148 [inline] netdev_start_xmit include/linux/netdevice.h:4157 [inline] xmit_one net/core/dev.c:3034 [inline] dev_hard_start_xmit+0x5df/0xc20 net/core/dev.c:3050 __dev_queue_xmit+0x2eea/0x3a70 net/core/dev.c:3569 dev_queue_xmit+0x4b/0x60 net/core/dev.c:3602 packet_snd net/packet/af_packet.c:2921 [inline] packet_sendmsg+0x7fb5/0x8ae0 net/packet/af_packet.c:2946 sock_sendmsg_nosec net/socket.c:642 [inline] sock_sendmsg net/socket.c:652 [inline] ___sys_sendmsg+0xe32/0x1250 net/socket.c:2126 __sys_sendmsg net/socket.c:2164 [inline] __do_sys_sendmsg net/socket.c:2173 [inline] __se_sys_sendmsg net/socket.c:2171 [inline] __x64_sys_sendmsg+0x32d/0x460 net/socket.c:2171 do_syscall_64+0x15b/0x220 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x63/0xe7 RIP: 0033:0x441149 Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 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 0f 83 db 0a fc ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ffdb58f66a8 EFLAGS: 00000286 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000441149 RDX: 0000000000000000 RSI: 0000000020000000 RDI: 0000000000000003 RBP: 00000000006cc018 R08: 0000000000000100 R09: 0000000000000100 R10: 0000000000000100 R11: 0000000000000286 R12: 00000000004020b0 R13: 0000000000402140 R14: 0000000000000000 R15: 0000000000000000 Uninit was created at: kmsan_save_stack_with_flags mm/kmsan/kmsan.c:256 [inline] kmsan_internal_poison_shadow+0xb8/0x1b0 mm/kmsan/kmsan.c:181 kmsan_kmalloc+0x98/0x100 mm/kmsan/kmsan_hooks.c:91 kmsan_slab_alloc+0x10/0x20 mm/kmsan/kmsan_hooks.c:100 slab_post_alloc_hook mm/slab.h:446 [inline] slab_alloc_node mm/slub.c:2720 [inline] __kmalloc_node_track_caller+0xb4c/0x11d0 mm/slub.c:4353 __kmalloc_reserve net/core/skbuff.c:138 [inline] __alloc_skb+0x2ce/0x9b0 net/core/skbuff.c:206 alloc_skb include/linux/skbuff.h:988 [inline] alloc_skb_with_frags+0x1d0/0xac0 net/core/skbuff.c:5272 sock_alloc_send_pskb+0xb47/0x1120 net/core/sock.c:2095 packet_alloc_skb net/packet/af_packet.c:2776 [inline] packet_snd net/packet/af_packet.c:2867 [inline] packet_sendmsg+0x6480/0x8ae0 net/packet/af_packet.c:2946 sock_sendmsg_nosec net/socket.c:642 [inline] sock_sendmsg net/socket.c:652 [inline] ___sys_sendmsg+0xe32/0x1250 net/socket.c:2126 __sys_sendmsg net/socket.c:2164 [inline] __do_sys_sendmsg net/socket.c:2173 [inline] __se_sys_sendmsg net/socket.c:2171 [inline] __x64_sys_sendmsg+0x32d/0x460 net/socket.c:2171 do_syscall_64+0x15b/0x220 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x63/0xe7 ==================================================================