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Paolo Abeni db57ccf0f2 netfilter: nat: cope with negative port range
syzbot reported a division by 0 bug in the netfilter nat code:

divide error: 0000 [#1] SMP KASAN
Dumping ftrace buffer:
    (ftrace buffer empty)
Modules linked in:
CPU: 1 PID: 4168 Comm: syzkaller034710 Not tainted 4.16.0-rc1+ #309
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:nf_nat_l4proto_unique_tuple+0x291/0x530
net/netfilter/nf_nat_proto_common.c:88
RSP: 0018:ffff8801b2466778 EFLAGS: 00010246
RAX: 000000000000f153 RBX: ffff8801b2466dd8 RCX: ffff8801b2466c7c
RDX: 0000000000000000 RSI: ffff8801b2466c58 RDI: ffff8801db5293ac
RBP: ffff8801b24667d8 R08: ffff8801b8ba6dc0 R09: ffffffff88af5900
R10: ffff8801b24666f0 R11: 0000000000000000 R12: 000000002990f153
R13: 0000000000000001 R14: 0000000000000000 R15: ffff8801b2466c7c
FS:  00000000017e3880(0000) GS:ffff8801db500000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000208fdfe4 CR3: 00000001b5340002 CR4: 00000000001606e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
  dccp_unique_tuple+0x40/0x50 net/netfilter/nf_nat_proto_dccp.c:30
  get_unique_tuple+0xc28/0x1c10 net/netfilter/nf_nat_core.c:362
  nf_nat_setup_info+0x1c2/0xe00 net/netfilter/nf_nat_core.c:406
  nf_nat_redirect_ipv6+0x306/0x730 net/netfilter/nf_nat_redirect.c:124
  redirect_tg6+0x7f/0xb0 net/netfilter/xt_REDIRECT.c:34
  ip6t_do_table+0xc2a/0x1a30 net/ipv6/netfilter/ip6_tables.c:365
  ip6table_nat_do_chain+0x65/0x80 net/ipv6/netfilter/ip6table_nat.c:41
  nf_nat_ipv6_fn+0x594/0xa80 net/ipv6/netfilter/nf_nat_l3proto_ipv6.c:302
  nf_nat_ipv6_local_fn+0x33/0x5d0
net/ipv6/netfilter/nf_nat_l3proto_ipv6.c:407
  ip6table_nat_local_fn+0x2c/0x40 net/ipv6/netfilter/ip6table_nat.c:69
  nf_hook_entry_hookfn include/linux/netfilter.h:120 [inline]
  nf_hook_slow+0xba/0x1a0 net/netfilter/core.c:483
  nf_hook include/linux/netfilter.h:243 [inline]
  NF_HOOK include/linux/netfilter.h:286 [inline]
  ip6_xmit+0x10ec/0x2260 net/ipv6/ip6_output.c:277
  inet6_csk_xmit+0x2fc/0x580 net/ipv6/inet6_connection_sock.c:139
  dccp_transmit_skb+0x9ac/0x10f0 net/dccp/output.c:142
  dccp_connect+0x369/0x670 net/dccp/output.c:564
  dccp_v6_connect+0xe17/0x1bf0 net/dccp/ipv6.c:946
  __inet_stream_connect+0x2d4/0xf00 net/ipv4/af_inet.c:620
  inet_stream_connect+0x58/0xa0 net/ipv4/af_inet.c:684
  SYSC_connect+0x213/0x4a0 net/socket.c:1639
  SyS_connect+0x24/0x30 net/socket.c:1620
  do_syscall_64+0x282/0x940 arch/x86/entry/common.c:287
  entry_SYSCALL_64_after_hwframe+0x26/0x9b
RIP: 0033:0x441c69
RSP: 002b:00007ffe50cc0be8 EFLAGS: 00000217 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: ffffffffffffffff RCX: 0000000000441c69
RDX: 000000000000001c RSI: 00000000208fdfe4 RDI: 0000000000000003
RBP: 00000000006cc018 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000538 R11: 0000000000000217 R12: 0000000000403590
R13: 0000000000403620 R14: 0000000000000000 R15: 0000000000000000
Code: 48 89 f0 83 e0 07 83 c0 01 38 d0 7c 08 84 d2 0f 85 46 02 00 00 48 8b
45 c8 44 0f b7 20 e8 88 97 04 fd 31 d2 41 0f b7 c4 4c 89 f9 <41> f7 f6 48
c1 e9 03 48 b8 00 00 00 00 00 fc ff df 0f b6 0c 01
RIP: nf_nat_l4proto_unique_tuple+0x291/0x530
net/netfilter/nf_nat_proto_common.c:88 RSP: ffff8801b2466778

The problem is that currently we don't have any check on the
configured port range. A port range == -1 triggers the bug, while
other negative values may require a very long time to complete the
following loop.

This commit addresses the issue swapping the two ends on negative
ranges. The check is performed in nf_nat_l4proto_unique_tuple() since
the nft nat loads the port values from nft registers at runtime.

v1 -> v2: use the correct 'Fixes' tag
v2 -> v3: update commit message, drop unneeded READ_ONCE()

Fixes: 5b1158e909 ("[NETFILTER]: Add NAT support for nf_conntrack")
Reported-by: syzbot+8012e198bd037f4871e5@syzkaller.appspotmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2018-02-14 21:05:40 +01:00
arch Merge branch 'akpm' (patches from Andrew) 2018-02-06 22:15:42 -08:00
block for-linus-20180204 2018-02-04 11:16:35 -08:00
certs License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2018-01-31 14:22:45 -08:00
Documentation Merge branch 'akpm' (patches from Andrew) 2018-02-06 22:15:42 -08:00
drivers net: ethernet: ti: cpsw: fix net watchdog timeout 2018-02-07 21:57:10 -05:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs Merge branch 'akpm' (patches from Andrew) 2018-02-06 22:15:42 -08:00
include Merge git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf 2018-02-07 13:55:20 -05:00
init membarrier: Provide core serializing command, *_SYNC_CORE 2018-02-05 21:35:03 +01:00
ipc ipc/mqueue.c: have RT tasks queue in by priority in wq_add() 2018-02-06 18:32:46 -08:00
kernel Merge branch 'akpm' (patches from Andrew) 2018-02-06 22:15:42 -08:00
lib Merge branch 'akpm' (patches from Andrew) 2018-02-06 22:15:42 -08:00
LICENSES LICENSES: Add MPL-1.1 license 2018-01-06 10:59:44 -07:00
mm Merge branch 'akpm' (patches from Andrew) 2018-02-06 22:15:42 -08:00
net netfilter: nat: cope with negative port range 2018-02-14 21:05:40 +01:00
samples sample/bpf: fix erspan metadata 2018-02-06 11:32:49 -05:00
scripts kasan: rework Kconfig settings 2018-02-06 18:32:47 -08:00
security pids: introduce find_get_task_by_vpid() helper 2018-02-06 18:32:46 -08:00
sound Driver Core updates for 4.16-rc1 2018-02-01 10:00:28 -08:00
tools Merge branch 'akpm' (patches from Andrew) 2018-02-06 22:15:42 -08:00
usr initramfs: fix initramfs rebuilds w/ compression after disabling 2017-11-03 07:39:19 -07:00
virt Currently, hardened usercopy performs dynamic bounds checking on slab 2018-02-03 16:25:42 -08:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore .gitignore: ignore ASN.1 auto generated files 2018-02-14 21:05:38 +01:00
.mailmap mailmap: update Mark Yao's email address 2018-01-04 16:45:09 -08:00
COPYING
CREDITS MAINTAINERS: update TPM driver infrastructure changes 2017-11-09 17:58:40 -08:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
MAINTAINERS Merge branch 'akpm' (patches from Andrew) 2018-02-06 22:15:42 -08:00
Makefile Makefile: introduce CONFIG_CC_STACKPROTECTOR_AUTO 2018-02-06 18:32:44 -08:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
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In order to build the documentation, use ``make htmldocs`` or
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There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
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the problems which may result by upgrading your kernel.