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Paolo Abeni db73501ebc netfilter: ebtables: handle string from userspace with care
[ Upstream commit 94c752f999 ]

strlcpy() can't be safely used on a user-space provided string,
as it can try to read beyond the buffer's end, if the latter is
not NULL terminated.

Leveraging the above, syzbot has been able to trigger the following
splat:

BUG: KASAN: stack-out-of-bounds in strlcpy include/linux/string.h:300
[inline]
BUG: KASAN: stack-out-of-bounds in compat_mtw_from_user
net/bridge/netfilter/ebtables.c:1957 [inline]
BUG: KASAN: stack-out-of-bounds in ebt_size_mwt
net/bridge/netfilter/ebtables.c:2059 [inline]
BUG: KASAN: stack-out-of-bounds in size_entry_mwt
net/bridge/netfilter/ebtables.c:2155 [inline]
BUG: KASAN: stack-out-of-bounds in compat_copy_entries+0x96c/0x14a0
net/bridge/netfilter/ebtables.c:2194
Write of size 33 at addr ffff8801b0abf888 by task syz-executor0/4504

CPU: 0 PID: 4504 Comm: syz-executor0 Not tainted 4.17.0-rc2+ #40
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+0x1b9/0x294 lib/dump_stack.c:113
  print_address_description+0x6c/0x20b mm/kasan/report.c:256
  kasan_report_error mm/kasan/report.c:354 [inline]
  kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412
  check_memory_region_inline mm/kasan/kasan.c:260 [inline]
  check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267
  memcpy+0x37/0x50 mm/kasan/kasan.c:303
  strlcpy include/linux/string.h:300 [inline]
  compat_mtw_from_user net/bridge/netfilter/ebtables.c:1957 [inline]
  ebt_size_mwt net/bridge/netfilter/ebtables.c:2059 [inline]
  size_entry_mwt net/bridge/netfilter/ebtables.c:2155 [inline]
  compat_copy_entries+0x96c/0x14a0 net/bridge/netfilter/ebtables.c:2194
  compat_do_replace+0x483/0x900 net/bridge/netfilter/ebtables.c:2285
  compat_do_ebt_set_ctl+0x2ac/0x324 net/bridge/netfilter/ebtables.c:2367
  compat_nf_sockopt net/netfilter/nf_sockopt.c:144 [inline]
  compat_nf_setsockopt+0x9b/0x140 net/netfilter/nf_sockopt.c:156
  compat_ip_setsockopt+0xff/0x140 net/ipv4/ip_sockglue.c:1279
  inet_csk_compat_setsockopt+0x97/0x120 net/ipv4/inet_connection_sock.c:1041
  compat_tcp_setsockopt+0x49/0x80 net/ipv4/tcp.c:2901
  compat_sock_common_setsockopt+0xb4/0x150 net/core/sock.c:3050
  __compat_sys_setsockopt+0x1ab/0x7c0 net/compat.c:403
  __do_compat_sys_setsockopt net/compat.c:416 [inline]
  __se_compat_sys_setsockopt net/compat.c:413 [inline]
  __ia32_compat_sys_setsockopt+0xbd/0x150 net/compat.c:413
  do_syscall_32_irqs_on arch/x86/entry/common.c:323 [inline]
  do_fast_syscall_32+0x345/0xf9b arch/x86/entry/common.c:394
  entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139
RIP: 0023:0xf7fb3cb9
RSP: 002b:00000000fff0c26c EFLAGS: 00000282 ORIG_RAX: 000000000000016e
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000000000
RDX: 0000000000000080 RSI: 0000000020000300 RDI: 00000000000005f4
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000

The buggy address belongs to the page:
page:ffffea0006c2afc0 count:0 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0x2fffc0000000000()
raw: 02fffc0000000000 0000000000000000 0000000000000000 00000000ffffffff
raw: 0000000000000000 ffffea0006c20101 0000000000000000 0000000000000000
page dumped because: kasan: bad access detected

Fix the issue replacing the unsafe function with strscpy() and
taking care of possible errors.

Fixes: 81e675c227 ("netfilter: ebtables: add CONFIG_COMPAT support")
Reported-and-tested-by: syzbot+4e42a04e0bc33cb6c087@syzkaller.appspotmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-07-08 15:30:51 +02:00
..
6lowpan License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
9p 9p/trans_virtio: discard zero-length reply 2018-02-22 15:42:30 +01:00
802 License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
8021q vlan: Fix out of order vlan headers with reorder header off 2018-05-30 07:52:16 +02:00
appletalk License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
atm net: atm: Fix potential Spectre v1 2018-05-16 10:10:29 +02:00
ax25 License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
batman-adv batman-adv: fix packet loss for broadcasted DHCP packets to a server 2018-05-30 07:52:19 +02:00
bluetooth Bluetooth: Fix connection if directed advertising and privacy is used 2018-04-19 08:56:19 +02:00
bpf bpf: Align packet data properly in program testing framework. 2017-05-02 11:46:28 -04:00
bridge netfilter: ebtables: handle string from userspace with care 2018-07-08 15:30:51 +02:00
caif License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
can can: af_can: canfd_rcv(): replace WARN_ONCE by pr_warn_once 2018-01-23 19:58:17 +01:00
ceph libceph, ceph: avoid memory leak when specifying same option several times 2018-05-30 07:52:04 +02:00
core rtnetlink: validate attributes in do_setlink() 2018-06-11 22:49:22 +02:00
dcb rtnetlink: make rtnl_register accept a flags parameter 2017-08-09 16:57:38 -07:00
dccp dccp: don't free ccid2_hc_tx_sock struct in dccp_disconnect() 2018-06-11 22:49:18 +02:00
decnet dn_getsockoptdecnet: move nf_{get/set}sockopt outside sock lock 2018-02-25 11:07:52 +01:00
dns_resolver KEYS: DNS: limit the length of option strings 2018-04-29 11:33:10 +02:00
dsa net: dsa: add error handling for pskb_trim_rcsum 2018-06-26 08:06:28 +08:00
ethernet networking: make skb_push & __skb_push return void pointers 2017-06-16 11:48:40 -04:00
hsr net/hsr: Check skb_put_padto() return value 2017-08-22 13:40:23 -07:00
ieee802154 ieee802154: 6lowpan: fix possible NULL deref in lowpan_device_event() 2018-03-31 18:10:40 +02:00
ife net: sched: ife: check on metadata length 2018-04-29 11:33:13 +02:00
ipv4 udp: fix rx queue len reported by diag and proc interface 2018-06-26 08:06:28 +08:00
ipv6 xfrm6: avoid potential infinite loop in _decode_session6() 2018-07-08 15:30:51 +02:00
ipx License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
iucv net/iucv: Free memory obtained by kzalloc 2018-03-31 18:10:41 +02:00
kcm kcm: Fix use-after-free caused by clonned sockets 2018-06-11 22:49:19 +02:00
key af_key: Always verify length of provided sadb_key 2018-06-16 09:45:14 +02:00
l2tp l2tp: revert "l2tp: fix missing print session offset info" 2018-05-19 10:20:27 +02:00
l3mdev
lapb net, lapb: convert lapb_cb.refcnt from atomic_t to refcount_t 2017-07-04 22:35:16 +01:00
llc llc: properly handle dev_queue_xmit() return value 2018-05-30 07:52:20 +02:00
mac80211 mac80211: use timeout from the AddBA response instead of the request 2018-06-21 04:02:55 +09:00
mac802154 License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
mpls mpls, nospec: Sanitize array index in mpls_label_ok() 2018-02-22 15:42:28 +01:00
ncsi net/ncsi: Fix length of GVI response packet 2017-10-21 01:56:38 +01:00
netfilter netfilter: nf_tables: use WARN_ON_ONCE instead of BUG_ON in nft_do_chain() 2018-07-08 15:30:50 +02:00
netlabel netlabel: If PF_INET6, check sk_buff ip header version 2018-05-30 07:52:40 +02:00
netlink netlink: fix uninit-value in netlink_sendmsg 2018-05-16 10:10:23 +02:00
netrom net, netrom: convert nr_node.refcount from atomic_t to refcount_t 2017-07-04 22:35:17 +01:00
nfc NFC: llcp: Limit size of SDP URI 2018-05-30 07:51:57 +02:00
nsh nsh: fix infinite loop 2018-05-19 10:20:26 +02:00
openvswitch openvswitch: Don't swap table in nlattr_set() after OVS_ATTR_NESTED is found 2018-05-19 10:20:24 +02:00
packet net: in virtio_net_hdr only add VLAN_HLEN to csum_start if payload holds vlan 2018-06-26 08:06:28 +08:00
phonet License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
psample MAINTAINERS: Update Yotam's E-mail 2017-11-01 12:19:03 +09:00
qrtr qrtr: add MODULE_ALIAS macro to smd 2018-05-30 07:52:05 +02:00
rds rds: ib: Fix missing call to rds_ib_dev_put in rds_ib_setup_qp 2018-06-21 04:02:48 +09:00
rfkill rfkill: gpio: fix memory leak in probe error path 2018-05-16 10:10:26 +02:00
rose net: Work around lockdep limitation in sockets that use sockets 2017-03-09 18:23:27 -08:00
rxrpc rxrpc: Fix the min security level for kernel calls 2018-06-21 04:02:56 +09:00
sched net/sched: act_simple: fix parsing of TCA_DEF_DATA 2018-06-26 08:06:28 +08:00
sctp sctp: not allow transport timeout value less than HZ/5 for hb_timer 2018-06-11 22:49:20 +02:00
smc smc: fix sendpage() call 2018-06-21 04:02:53 +09:00
strparser strparser: Fix incorrect strp->need_bytes value. 2018-04-29 11:33:13 +02:00
sunrpc xprtrdma: Return -ENOBUFS when no pages are available 2018-07-03 11:24:54 +02:00
switchdev net: switchdev: Remove bridge bypass support from switchdev 2017-08-07 14:48:48 -07:00
tipc tipc: eliminate KMSAN uninit-value in strcmp complaint 2018-06-21 04:02:56 +09:00
tls tls: fix use-after-free in tls_push_record 2018-06-26 08:06:29 +08:00
unix License cleanup: add SPDX license identifiers to some files 2017-11-02 10:04:46 -07:00
vmw_vsock VSOCK: fix outdated sk_state value in hvs_release() 2018-02-25 11:07:59 +01:00
wimax License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
wireless cfg80211: clear wep keys after disconnection 2018-05-30 07:51:58 +02:00
x25 License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
xfrm xfrm: Fix transport mode skb control buffer usage. 2018-05-30 07:52:19 +02:00
Kconfig net: Remove CONFIG_NETFILTER_DEBUG and _ASSERT() macros. 2017-09-04 13:25:20 +02:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
compat.c net: support compat 64-bit time in {s,g}etsockopt 2018-05-19 10:20:24 +02:00
socket.c socket: close race condition between sock_close() and sockfs_setattr() 2018-06-26 08:06:28 +08:00
sysctl_net.c sysctl: Remove dead register_sysctl_root 2017-04-16 23:42:49 -05:00