linux-stable.git/net/netfilter, branch v3.16.65

netfilter: nf_tables: fix use-after-free when deleting compat expressions

2019-02-11T17:54:03+00:00

commit 29e3880109e357fdc607b4393f8308cef6af9413 upstream.

nft_compat ops do not have static storage duration, unlike all other
expressions.

When nf_tables_expr_destroy() returns, expr->ops might have been
free'd already, so we need to store next address before calling
expression destructor.

For same reason, we can't deref match pointer after nft_xt_put().

This can be easily reproduced by adding msleep() before
nft_match_destroy() returns.

Fixes: 0ca743a55991 ("netfilter: nf_tables: add compatibility layer for x_tables")
Reported-by: Pablo Neira Ayuso 
Signed-off-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso 
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings

netfilter: nf_tables: fix oob access

2019-02-11T17:54:03+00:00

commit 3e38df136e453aa69eb4472108ebce2fb00b1ba6 upstream.

BUG: KASAN: slab-out-of-bounds in nf_tables_rule_destroy+0xf1/0x130 at addr ffff88006a4c35c8
Read of size 8 by task nft/1607

When we've destroyed last valid expr, nft_expr_next() returns an invalid expr.
We must not dereference it unless it passes != nft_expr_last() check.

Signed-off-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso 
Signed-off-by: Ben Hutchings

netfilter: nf_tables: don't use position attribute on rule replacement

2019-02-11T17:54:01+00:00

commit 447750f281abef547be44fdcfe3bc4447b3115a8 upstream.

Its possible to set both HANDLE and POSITION when replacing a rule.
In this case, the rule at POSITION gets replaced using the
userspace-provided handle.  Rule handles are supposed to be generated
by the kernel only.

Duplicate handles should be harmless, however better disable this "feature"
by only checking for the POSITION attribute on insert operations.

Fixes: 5e94846686d0 ("netfilter: nf_tables: add insert operation")
Signed-off-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso 
[bwh: Backported to 3.16:
 - Don't use extack
 - Adjust context]
Signed-off-by: Ben Hutchings

netfilter: xt_IDLETIMER: add sysfs filename checking routine

2019-02-11T17:53:45+00:00

commit 54451f60c8fa061af9051a53be9786393947367c upstream.

When IDLETIMER rule is added, sysfs file is created under
/sys/class/xt_idletimer/timers/
But some label name shouldn't be used.
".", "..", "power", "uevent", "subsystem", etc...
So that sysfs filename checking routine is needed.

test commands:
   %iptables -I INPUT -j IDLETIMER --timeout 1 --label "power"

splat looks like:
[95765.423132] sysfs: cannot create duplicate filename '/devices/virtual/xt_idletimer/timers/power'
[95765.433418] CPU: 0 PID: 8446 Comm: iptables Not tainted 4.19.0-rc6+ #20
[95765.449755] Call Trace:
[95765.449755]  dump_stack+0xc9/0x16b
[95765.449755]  ? show_regs_print_info+0x5/0x5
[95765.449755]  sysfs_warn_dup+0x74/0x90
[95765.449755]  sysfs_add_file_mode_ns+0x352/0x500
[95765.449755]  sysfs_create_file_ns+0x179/0x270
[95765.449755]  ? sysfs_add_file_mode_ns+0x500/0x500
[95765.449755]  ? idletimer_tg_checkentry+0x3e5/0xb1b [xt_IDLETIMER]
[95765.449755]  ? rcu_read_lock_sched_held+0x114/0x130
[95765.449755]  ? __kmalloc_track_caller+0x211/0x2b0
[95765.449755]  ? memcpy+0x34/0x50
[95765.449755]  idletimer_tg_checkentry+0x4e2/0xb1b [xt_IDLETIMER]
[ ... ]

Fixes: 0902b469bd25 ("netfilter: xtables: idletimer target implementation")
Signed-off-by: Taehee Yoo 
Signed-off-by: Pablo Neira Ayuso 
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings

netfilter: x_tables: add and use xt_check_proc_name

2019-02-11T17:53:45+00:00

commit b1d0a5d0cba4597c0394997b2d5fced3e3841b4e upstream.

recent and hashlimit both create /proc files, but only check that
name is 0 terminated.

This can trigger WARN() from procfs when name is "" or "/".
Add helper for this and then use it for both.

Cc: Eric Dumazet 
Reported-by: Eric Dumazet 
Reported-by: 
Signed-off-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso 
[bwh: Backported to 3.16:
 - xt_hashlimit has only one check function
 - Adjust context]
Signed-off-by: Ben Hutchings

netfilter: nf_tables: fix register ordering

2018-12-16T22:08:48+00:00

commit d209df3e7f7002d9099fdb0f6df0f972b4386a63 upstream.

We must register nfnetlink ops last, as that exposes nf_tables to
userspace.  Without this, we could theoretically get nfnetlink request
before net->nft state has been initialized.

Fixes: 99633ab29b213 ("netfilter: nf_tables: complete net namespace support")
Signed-off-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso 
[bwh: Backported to 3.16:
 - We don't call nft_chain_filter_{init,fini}() or
   {,un}register_netdevice_notifier()
 - Adjust context]
Signed-off-by: Ben Hutchings

netfilter: nft_set: fix allocation size overflow in privsize callback.

2018-12-16T22:08:48+00:00

commit 4ef360dd6a65f6ef337645e1b65e744034754b19 upstream.

In order to determine allocation size of set, ->privsize is invoked.
At this point, both desc->size and size of each data structure of set
are used. desc->size means number of element that is given by user.
desc->size is u32 type. so that upperlimit of set element is 4294967295.
but return type of ->privsize is also u32. hence overflow can occurred.

test commands:
   %nft add table ip filter
   %nft add set ip filter hash1 { type ipv4_addr \; size 4294967295 \; }
   %nft list ruleset

splat looks like:
[ 1239.202910] kasan: CONFIG_KASAN_INLINE enabled
[ 1239.208788] kasan: GPF could be caused by NULL-ptr deref or user memory access
[ 1239.217625] general protection fault: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN PTI
[ 1239.219329] CPU: 0 PID: 1603 Comm: nft Not tainted 4.18.0-rc5+ #7
[ 1239.229091] RIP: 0010:nft_hash_walk+0x1d2/0x310 [nf_tables_set]
[ 1239.229091] Code: 84 d2 7f 10 4c 89 e7 89 44 24 38 e8 d8 5a 17 e0 8b 44 24 38 48 8d 7b 10 41 0f b6 0c 24 48 89 fa 48 89 fe 48 c1 ea 03 83 e6 07 <42> 0f b6 14 3a 40 38 f2 7f 1a 84 d2 74 16
[ 1239.229091] RSP: 0018:ffff8801118cf358 EFLAGS: 00010246
[ 1239.229091] RAX: 0000000000000000 RBX: 0000000000020400 RCX: 0000000000000001
[ 1239.229091] RDX: 0000000000004082 RSI: 0000000000000000 RDI: 0000000000020410
[ 1239.229091] RBP: ffff880114d5a988 R08: 0000000000007e94 R09: ffff880114dd8030
[ 1239.229091] R10: ffff880114d5a988 R11: ffffed00229bb006 R12: ffff8801118cf4d0
[ 1239.229091] R13: ffff8801118cf4d8 R14: 0000000000000000 R15: dffffc0000000000
[ 1239.229091] FS:  00007f5a8fe0b700(0000) GS:ffff88011b600000(0000) knlGS:0000000000000000
[ 1239.229091] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 1239.229091] CR2: 00007f5a8ecc27b0 CR3: 000000010608e000 CR4: 00000000001006f0
[ 1239.229091] Call Trace:
[ 1239.229091]  ? nft_hash_remove+0xf0/0xf0 [nf_tables_set]
[ 1239.229091]  ? memset+0x1f/0x40
[ 1239.229091]  ? __nla_reserve+0x9f/0xb0
[ 1239.229091]  ? memcpy+0x34/0x50
[ 1239.229091]  nf_tables_dump_set+0x9a1/0xda0 [nf_tables]
[ 1239.229091]  ? __kmalloc_reserve.isra.29+0x2e/0xa0
[ 1239.229091]  ? nft_chain_hash_obj+0x630/0x630 [nf_tables]
[ 1239.229091]  ? nf_tables_commit+0x2c60/0x2c60 [nf_tables]
[ 1239.229091]  netlink_dump+0x470/0xa20
[ 1239.229091]  __netlink_dump_start+0x5ae/0x690
[ 1239.229091]  nft_netlink_dump_start_rcu+0xd1/0x160 [nf_tables]
[ 1239.229091]  nf_tables_getsetelem+0x2e5/0x4b0 [nf_tables]
[ 1239.229091]  ? nft_get_set_elem+0x440/0x440 [nf_tables]
[ 1239.229091]  ? nft_chain_hash_obj+0x630/0x630 [nf_tables]
[ 1239.229091]  ? nf_tables_dump_obj_done+0x70/0x70 [nf_tables]
[ 1239.229091]  ? nla_parse+0xab/0x230
[ 1239.229091]  ? nft_get_set_elem+0x440/0x440 [nf_tables]
[ 1239.229091]  nfnetlink_rcv_msg+0x7f0/0xab0 [nfnetlink]
[ 1239.229091]  ? nfnetlink_bind+0x1d0/0x1d0 [nfnetlink]
[ 1239.229091]  ? debug_show_all_locks+0x290/0x290
[ 1239.229091]  ? sched_clock_cpu+0x132/0x170
[ 1239.229091]  ? find_held_lock+0x39/0x1b0
[ 1239.229091]  ? sched_clock_local+0x10d/0x130
[ 1239.229091]  netlink_rcv_skb+0x211/0x320
[ 1239.229091]  ? nfnetlink_bind+0x1d0/0x1d0 [nfnetlink]
[ 1239.229091]  ? netlink_ack+0x7b0/0x7b0
[ 1239.229091]  ? ns_capable_common+0x6e/0x110
[ 1239.229091]  nfnetlink_rcv+0x2d1/0x310 [nfnetlink]
[ 1239.229091]  ? nfnetlink_rcv_batch+0x10f0/0x10f0 [nfnetlink]
[ 1239.229091]  ? netlink_deliver_tap+0x829/0x930
[ 1239.229091]  ? lock_acquire+0x265/0x2e0
[ 1239.229091]  netlink_unicast+0x406/0x520
[ 1239.509725]  ? netlink_attachskb+0x5b0/0x5b0
[ 1239.509725]  ? find_held_lock+0x39/0x1b0
[ 1239.509725]  netlink_sendmsg+0x987/0xa20
[ 1239.509725]  ? netlink_unicast+0x520/0x520
[ 1239.509725]  ? _copy_from_user+0xa9/0xc0
[ 1239.509725]  __sys_sendto+0x21a/0x2c0
[ 1239.509725]  ? __ia32_sys_getpeername+0xa0/0xa0
[ 1239.509725]  ? retint_kernel+0x10/0x10
[ 1239.509725]  ? sched_clock_cpu+0x132/0x170
[ 1239.509725]  ? find_held_lock+0x39/0x1b0
[ 1239.509725]  ? lock_downgrade+0x540/0x540
[ 1239.509725]  ? up_read+0x1c/0x100
[ 1239.509725]  ? __do_page_fault+0x763/0x970
[ 1239.509725]  ? retint_user+0x18/0x18
[ 1239.509725]  __x64_sys_sendto+0x177/0x180
[ 1239.509725]  do_syscall_64+0xaa/0x360
[ 1239.509725]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 1239.509725] RIP: 0033:0x7f5a8f468e03
[ 1239.509725] Code: 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb d0 0f 1f 84 00 00 00 00 00 83 3d 49 c9 2b 00 00 75 13 49 89 ca b8 2c 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 34 c3 48 83 ec 08 e8
[ 1239.509725] RSP: 002b:00007ffd78d0b778 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
[ 1239.509725] RAX: ffffffffffffffda RBX: 00007ffd78d0c890 RCX: 00007f5a8f468e03
[ 1239.509725] RDX: 0000000000000034 RSI: 00007ffd78d0b7e0 RDI: 0000000000000003
[ 1239.509725] RBP: 00007ffd78d0b7d0 R08: 00007f5a8f15c160 R09: 000000000000000c
[ 1239.509725] R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffd78d0b7e0
[ 1239.509725] R13: 0000000000000034 R14: 00007f5a8f9aff60 R15: 00005648040094b0
[ 1239.509725] Modules linked in: nf_tables_set nf_tables nfnetlink ip_tables x_tables
[ 1239.670713] ---[ end trace 39375adcda140f11 ]---
[ 1239.676016] RIP: 0010:nft_hash_walk+0x1d2/0x310 [nf_tables_set]
[ 1239.682834] Code: 84 d2 7f 10 4c 89 e7 89 44 24 38 e8 d8 5a 17 e0 8b 44 24 38 48 8d 7b 10 41 0f b6 0c 24 48 89 fa 48 89 fe 48 c1 ea 03 83 e6 07 <42> 0f b6 14 3a 40 38 f2 7f 1a 84 d2 74 16
[ 1239.705108] RSP: 0018:ffff8801118cf358 EFLAGS: 00010246
[ 1239.711115] RAX: 0000000000000000 RBX: 0000000000020400 RCX: 0000000000000001
[ 1239.719269] RDX: 0000000000004082 RSI: 0000000000000000 RDI: 0000000000020410
[ 1239.727401] RBP: ffff880114d5a988 R08: 0000000000007e94 R09: ffff880114dd8030
[ 1239.735530] R10: ffff880114d5a988 R11: ffffed00229bb006 R12: ffff8801118cf4d0
[ 1239.743658] R13: ffff8801118cf4d8 R14: 0000000000000000 R15: dffffc0000000000
[ 1239.751785] FS:  00007f5a8fe0b700(0000) GS:ffff88011b600000(0000) knlGS:0000000000000000
[ 1239.760993] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 1239.767560] CR2: 00007f5a8ecc27b0 CR3: 000000010608e000 CR4: 00000000001006f0
[ 1239.775679] Kernel panic - not syncing: Fatal exception
[ 1239.776630] Kernel Offset: 0x1f000000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff)
[ 1239.776630] Rebooting in 5 seconds..

Fixes: 20a69341f2d0 ("netfilter: nf_tables: add netlink set API")
Signed-off-by: Taehee Yoo 
Signed-off-by: Pablo Neira Ayuso 
[bwh: Backported to 3.16:
 - Drop changes to nft_rhash_privsize() and in nft_set_bitmap.c
 - Adjust filenames]
Signed-off-by: Ben Hutchings

netfilter: nf_log: don't hold nf_log_mutex during user access

2018-11-20T18:05:28+00:00

commit ce00bf07cc95a57cd20b208e02b3c2604e532ae8 upstream.

The old code would indefinitely block other users of nf_log_mutex if
a userspace access in proc_dostring() blocked e.g. due to a userfaultfd
region. Fix it by moving proc_dostring() out of the locked region.

This is a followup to commit 266d07cb1c9a ("netfilter: nf_log: fix
sleeping function called from invalid context"), which changed this code
from using rcu_read_lock() to taking nf_log_mutex.

Fixes: 266d07cb1c9a ("netfilter: nf_log: fix sleeping function calle[...]")
Signed-off-by: Jann Horn 
Signed-off-by: Pablo Neira Ayuso 
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings

netfilter: nf_queue: augment nfqa_cfg_policy

2018-11-20T18:05:17+00:00

commit ba062ebb2cd561d404e0fba8ee4b3f5ebce7cbfc upstream.

Three attributes are currently not verified, thus can trigger KMSAN
warnings such as :

BUG: KMSAN: uninit-value in __arch_swab32 arch/x86/include/uapi/asm/swab.h:10 [inline]
BUG: KMSAN: uninit-value in __fswab32 include/uapi/linux/swab.h:59 [inline]
BUG: KMSAN: uninit-value in nfqnl_recv_config+0x939/0x17d0 net/netfilter/nfnetlink_queue.c:1268
CPU: 1 PID: 4521 Comm: syz-executor120 Not tainted 4.17.0+ #5
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+0x185/0x1d0 lib/dump_stack.c:113
 kmsan_report+0x188/0x2a0 mm/kmsan/kmsan.c:1117
 __msan_warning_32+0x70/0xc0 mm/kmsan/kmsan_instr.c:620
 __arch_swab32 arch/x86/include/uapi/asm/swab.h:10 [inline]
 __fswab32 include/uapi/linux/swab.h:59 [inline]
 nfqnl_recv_config+0x939/0x17d0 net/netfilter/nfnetlink_queue.c:1268
 nfnetlink_rcv_msg+0xb2e/0xc80 net/netfilter/nfnetlink.c:212
 netlink_rcv_skb+0x37e/0x600 net/netlink/af_netlink.c:2448
 nfnetlink_rcv+0x2fe/0x680 net/netfilter/nfnetlink.c:513
 netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline]
 netlink_unicast+0x1680/0x1750 net/netlink/af_netlink.c:1336
 netlink_sendmsg+0x104f/0x1350 net/netlink/af_netlink.c:1901
 sock_sendmsg_nosec net/socket.c:629 [inline]
 sock_sendmsg net/socket.c:639 [inline]
 ___sys_sendmsg+0xec8/0x1320 net/socket.c:2117
 __sys_sendmsg net/socket.c:2155 [inline]
 __do_sys_sendmsg net/socket.c:2164 [inline]
 __se_sys_sendmsg net/socket.c:2162 [inline]
 __x64_sys_sendmsg+0x331/0x460 net/socket.c:2162
 do_syscall_64+0x15b/0x230 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x43fd59
RSP: 002b:00007ffde0e30d28 EFLAGS: 00000213 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 000000000043fd59
RDX: 0000000000000000 RSI: 0000000020000080 RDI: 0000000000000003
RBP: 00000000006ca018 R08: 00000000004002c8 R09: 00000000004002c8
R10: 00000000004002c8 R11: 0000000000000213 R12: 0000000000401680
R13: 0000000000401710 R14: 0000000000000000 R15: 0000000000000000

Uninit was created at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:279 [inline]
 kmsan_internal_poison_shadow+0xb8/0x1b0 mm/kmsan/kmsan.c:189
 kmsan_kmalloc+0x94/0x100 mm/kmsan/kmsan.c:315
 kmsan_slab_alloc+0x10/0x20 mm/kmsan/kmsan.c:322
 slab_post_alloc_hook mm/slab.h:446 [inline]
 slab_alloc_node mm/slub.c:2753 [inline]
 __kmalloc_node_track_caller+0xb35/0x11b0 mm/slub.c:4395
 __kmalloc_reserve net/core/skbuff.c:138 [inline]
 __alloc_skb+0x2cb/0x9e0 net/core/skbuff.c:206
 alloc_skb include/linux/skbuff.h:988 [inline]
 netlink_alloc_large_skb net/netlink/af_netlink.c:1182 [inline]
 netlink_sendmsg+0x76e/0x1350 net/netlink/af_netlink.c:1876
 sock_sendmsg_nosec net/socket.c:629 [inline]
 sock_sendmsg net/socket.c:639 [inline]
 ___sys_sendmsg+0xec8/0x1320 net/socket.c:2117
 __sys_sendmsg net/socket.c:2155 [inline]
 __do_sys_sendmsg net/socket.c:2164 [inline]
 __se_sys_sendmsg net/socket.c:2162 [inline]
 __x64_sys_sendmsg+0x331/0x460 net/socket.c:2162
 do_syscall_64+0x15b/0x230 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Fixes: fdb694a01f1f ("netfilter: Add fail-open support")
Fixes: 829e17a1a602 ("[NETFILTER]: nfnetlink_queue: allow changing queue length through netlink")
Signed-off-by: Eric Dumazet 
Reported-by: syzbot 
Signed-off-by: Pablo Neira Ayuso 
[bwh: Backported to 3.16: adjust filename]
Signed-off-by: Ben Hutchings

ipvs: fix buffer overflow with sync daemon and service

2018-10-21T07:46:16+00:00

commit 52f96757905bbf0edef47f3ee6c7c784e7f8ff8a upstream.

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@syzkaller.appspotmail.com
Fixes: e4ff67513096 ("ipvs: add sync_maxlen parameter for the sync daemon")
Fixes: 4da62fc70d7c ("[IPVS]: Fix for overflows")
Signed-off-by: Julian Anastasov 
Acked-by: Simon Horman 
Signed-off-by: Pablo Neira Ayuso 
[bwh: Backported to 3.16: Interface name is copied in start_sync_thread(),
 not do_ip_vs_set_ctl()]
Signed-off-by: Ben Hutchings