On Wed, May 23, 2018 at 10:19:09AM +0200, Simon Horman wrote:
> On Sat, May 19, 2018 at 06:22:35PM +0300, Julian Anastasov wrote:
> > syzkaller reports for buffer overflow for interface name
> > when starting sync daemons [1]
> >
> > What we do is that we copy user structure into larger stack
> > buffer but later we search NUL past the stack buffer.
> > The same happens for sched_name when adding/editing virtual server.
> >
> > We are restricted by IP_VS_SCHEDNAME_MAXLEN and IP_VS_IFNAME_MAXLEN
> > being used as size in include/uapi/linux/ip_vs.h, so they
> > include the space for NUL.
> >
> > As using strlcpy is wrong for unsafe source, replace it with
> > strscpy and add checks to return EINVAL if source string is not
> > NUL-terminated. The incomplete strlcpy fix comes from 2.6.13.
> >
> > For the netlink interface reduce the len parameter for
> > IPVS_DAEMON_ATTR_MCAST_IFN and IPVS_SVC_ATTR_SCHED_NAME,
> > so that we get proper EINVAL.
> >
> > [1]
> > 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
> >
> > Reported-and-tested-by: syzbot+aac887f77319868646df@xxxxxxxxxxxxxxxxxxxxxxxxx
> > Fixes: e4ff67513096 ("ipvs: add sync_maxlen parameter for the sync daemon")
> > Fixes: 4da62fc70d7c ("[IPVS]: Fix for overflows")
> > Signed-off-by: Julian Anastasov <ja@xxxxxx>
>
> Acked-by: Simon Horman <horms+renesas@xxxxxxxxxxxx>
Applied to nf.git, thanks!
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