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Date:   Thu, 17 May 2018 01:43:36 +0300 (EEST)
From:   Julian Anastasov <ja@ssi.bg>
To:     syzbot <syzbot+aac887f77319868646df@syzkaller.appspotmail.com>
cc:     coreteam@netfilter.org, davem@davemloft.net, fw@strlen.de,
        horms@verge.net.au, kadlec@blackhole.kfki.hu,
        linux-kernel@vger.kernel.org, lvs-devel@vger.kernel.org,
        netdev@vger.kernel.org, netfilter-devel@vger.kernel.org,
        pablo@netfilter.org, syzkaller-bugs@googlegroups.com,
        wensong@linux-vs.org
Subject: Re: kernel BUG at lib/string.c:LINE! (4)
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	Hello,

On Wed, 16 May 2018, syzbot wrote:

> Hello,
> 
> syzbot found the following crash on:
> 
> HEAD commit:    0b7d9978406f Merge branch 'Microsemi-Ocelot-Ethernet-switc..
> git tree:       net-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=16e91017800000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=b632d8e2c2ab2c1
> dashboard link: https://syzkaller.appspot.com/bug?extid=aac887f77319868646df
> compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
> syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=1665d637800000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10517107800000
> 
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+aac887f77319868646df@syzkaller.appspotmail.com
> 
> IPVS: Unknown mcast interface: veth1_to???a????????????
> IPVS: Unknown mcast interface: veth1_to???a????????????
> IPVS: Unknown mcast interface: veth1_to???a????????????
> detected buffer overflow in strlen
> ------------[ cut here ]------------
> kernel BUG at lib/string.c:1052!
> invalid opcode: 0000 [#1] SMP KASAN
> Dumping ftrace buffer:
>   (ftrace buffer empty)
> Modules linked in:
> CPU: 1 PID: 373 Comm: syz-executor936 Not tainted 4.17.0-rc4+ #45
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google
> 01/01/2011
> RIP: 0010:fortify_panic+0x13/0x20 lib/string.c:1051
> RSP: 0018:ffff8801c976f800 EFLAGS: 00010282
> RAX: 0000000000000022 RBX: 0000000000000040 RCX: 0000000000000000
> RDX: 0000000000000022 RSI: ffffffff8160f6f1 RDI: ffffed00392edef6
> RBP: ffff8801c976f800 R08: ffff8801cf4c62c0 R09: ffffed003b5e4fb0
> R10: ffffed003b5e4fb0 R11: ffff8801daf27d87 R12: ffff8801c976fa20
> R13: ffff8801c976fae4 R14: ffff8801c976fae0 R15: 000000000000048b
> FS:  00007fd99f75e700(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00000000200001c0 CR3: 00000001d6843000 CR4: 00000000001406e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
> strlen include/linux/string.h:270 [inline]
> strlcpy include/linux/string.h:293 [inline]
> do_ip_vs_set_ctl+0x31c/0x1d00 net/netfilter/ipvs/ip_vs_ctl.c:2388
> nf_sockopt net/netfilter/nf_sockopt.c:106 [inline]
> nf_setsockopt+0x7d/0xd0 net/netfilter/nf_sockopt.c:115
> ip_setsockopt+0xd8/0xf0 net/ipv4/ip_sockglue.c:1253
> udp_setsockopt+0x62/0xa0 net/ipv4/udp.c:2487
> ipv6_setsockopt+0x149/0x170 net/ipv6/ipv6_sockglue.c:917
> tcp_setsockopt+0x93/0xe0 net/ipv4/tcp.c:3057
> sock_common_setsockopt+0x9a/0xe0 net/core/sock.c:3046
> __sys_setsockopt+0x1bd/0x390 net/socket.c:1903
> __do_sys_setsockopt net/socket.c:1914 [inline]
> __se_sys_setsockopt net/socket.c:1911 [inline]
> __x64_sys_setsockopt+0xbe/0x150 net/socket.c:1911
> do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
> entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x447369
> RSP: 002b:00007fd99f75dda8 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
> RAX: ffffffffffffffda RBX: 00000000006e39e4 RCX: 0000000000447369
> RDX: 000000000000048b RSI: 0000000000000000 RDI: 0000000000000003
> RBP: 0000000000000000 R08: 0000000000000018 R09: 0000000000000000
> R10: 00000000200001c0 R11: 0000000000000246 R12: 00000000006e39e0
> R13: 75a1ff93f0896195 R14: 6f745f3168746576 R15: 0000000000000001
> Code: 08 5b 41 5c 41 5d 41 5e 41 5f 5d c3 0f 0b 48 89 df e8 d2 8f 48 fa eb de
> 55 48 89 fe 48 c7 c7 60 65 64 88 48 89 e5 e8 91 dd f3 f9 <0f> 0b 90 90 90 90
> 90 90 90 90 90 90 90 55 48 89 e5 41 57 41 56
> RIP: fortify_panic+0x13/0x20 lib/string.c:1051 RSP: ffff8801c976f800
> ---[ end trace 624046f2d9af7702 ]---

	Just to let you know that I tested a patch with
the syzbot, will do more tests before submitting...

Regards

--
Julian Anastasov <ja@ssi.bg>