alistair23-linux/net/core
Eric Dumazet 501a90c945 inet: protect against too small mtu values.
syzbot was once again able to crash a host by setting a very small mtu
on loopback device.

Let's make inetdev_valid_mtu() available in include/net/ip.h,
and use it in ip_setup_cork(), so that we protect both ip_append_page()
and __ip_append_data()

Also add a READ_ONCE() when the device mtu is read.

Pairs this lockless read with one WRITE_ONCE() in __dev_set_mtu(),
even if other code paths might write over this field.

Add a big comment in include/linux/netdevice.h about dev->mtu
needing READ_ONCE()/WRITE_ONCE() annotations.

Hopefully we will add the missing ones in followup patches.

[1]

refcount_t: saturated; leaking memory.
WARNING: CPU: 0 PID: 9464 at lib/refcount.c:22 refcount_warn_saturate+0x138/0x1f0 lib/refcount.c:22
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 9464 Comm: syz-executor850 Not tainted 5.4.0-syzkaller #0
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+0x197/0x210 lib/dump_stack.c:118
 panic+0x2e3/0x75c kernel/panic.c:221
 __warn.cold+0x2f/0x3e kernel/panic.c:582
 report_bug+0x289/0x300 lib/bug.c:195
 fixup_bug arch/x86/kernel/traps.c:174 [inline]
 fixup_bug arch/x86/kernel/traps.c:169 [inline]
 do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:267
 do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:286
 invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027
RIP: 0010:refcount_warn_saturate+0x138/0x1f0 lib/refcount.c:22
Code: 06 31 ff 89 de e8 c8 f5 e6 fd 84 db 0f 85 6f ff ff ff e8 7b f4 e6 fd 48 c7 c7 e0 71 4f 88 c6 05 56 a6 a4 06 01 e8 c7 a8 b7 fd <0f> 0b e9 50 ff ff ff e8 5c f4 e6 fd 0f b6 1d 3d a6 a4 06 31 ff 89
RSP: 0018:ffff88809689f550 EFLAGS: 00010286
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff815e4336 RDI: ffffed1012d13e9c
RBP: ffff88809689f560 R08: ffff88809c50a3c0 R09: fffffbfff15d31b1
R10: fffffbfff15d31b0 R11: ffffffff8ae98d87 R12: 0000000000000001
R13: 0000000000040100 R14: ffff888099041104 R15: ffff888218d96e40
 refcount_add include/linux/refcount.h:193 [inline]
 skb_set_owner_w+0x2b6/0x410 net/core/sock.c:1999
 sock_wmalloc+0xf1/0x120 net/core/sock.c:2096
 ip_append_page+0x7ef/0x1190 net/ipv4/ip_output.c:1383
 udp_sendpage+0x1c7/0x480 net/ipv4/udp.c:1276
 inet_sendpage+0xdb/0x150 net/ipv4/af_inet.c:821
 kernel_sendpage+0x92/0xf0 net/socket.c:3794
 sock_sendpage+0x8b/0xc0 net/socket.c:936
 pipe_to_sendpage+0x2da/0x3c0 fs/splice.c:458
 splice_from_pipe_feed fs/splice.c:512 [inline]
 __splice_from_pipe+0x3ee/0x7c0 fs/splice.c:636
 splice_from_pipe+0x108/0x170 fs/splice.c:671
 generic_splice_sendpage+0x3c/0x50 fs/splice.c:842
 do_splice_from fs/splice.c:861 [inline]
 direct_splice_actor+0x123/0x190 fs/splice.c:1035
 splice_direct_to_actor+0x3b4/0xa30 fs/splice.c:990
 do_splice_direct+0x1da/0x2a0 fs/splice.c:1078
 do_sendfile+0x597/0xd00 fs/read_write.c:1464
 __do_sys_sendfile64 fs/read_write.c:1525 [inline]
 __se_sys_sendfile64 fs/read_write.c:1511 [inline]
 __x64_sys_sendfile64+0x1dd/0x220 fs/read_write.c:1511
 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x441409
Code: e8 ac e8 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 eb 08 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fffb64c4f78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000441409
RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000005
RBP: 0000000000073b8a R08: 0000000000000010 R09: 0000000000000010
R10: 0000000000010001 R11: 0000000000000246 R12: 0000000000402180
R13: 0000000000402210 R14: 0000000000000000 R15: 0000000000000000
Kernel Offset: disabled
Rebooting in 86400 seconds..

Fixes: 1470ddf7f8 ("inet: Remove explicit write references to sk/inet in ip_append_data")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-12-07 11:55:11 -08:00
..
bpf_sk_storage.c bpf: Switch bpf_map ref counter to atomic64_t so bpf_map_inc() never fails 2019-11-18 11:41:59 +01:00
datagram.c net: add READ_ONCE() annotation in __skb_wait_for_more_packets() 2019-10-28 13:33:41 -07:00
datagram.h net/core: Allow the compiler to verify declaration and definition consistency 2019-03-27 13:49:44 -07:00
dev.c inet: protect against too small mtu values. 2019-12-07 11:55:11 -08:00
dev_addr_lists.c net: remove unnecessary variables and callback 2019-10-24 14:53:49 -07:00
dev_ioctl.c net/core: Document all dev_ioctl() arguments 2019-03-27 13:49:43 -07:00
devlink.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-11-16 21:51:42 -08:00
drop_monitor.c drop_monitor: Better sanitize notified packets 2019-09-16 21:39:27 +02:00
dst.c net: print proper warning on dst underflow 2019-09-26 09:05:56 +02:00
dst_cache.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
ethtool.c net: Zeroing the structure ethtool_wolinfo in ethtool_get_wol() 2019-10-26 11:20:10 -07:00
failover.c failover: allow name change on IFF_UP slave interfaces 2019-04-10 22:12:26 -07:00
fib_notifier.c net: fib_notifier: propagate extack down to the notifier block callback 2019-10-04 11:10:56 -07:00
fib_rules.c net: fib_notifier: propagate extack down to the notifier block callback 2019-10-04 11:10:56 -07:00
filter.c net: skmsg: fix TLS 1.3 crash with full sk_msg 2019-11-28 22:40:29 -08:00
flow_dissector.c net: dsa: fix flow dissection on Tx path 2019-12-06 20:20:17 -08:00
flow_offload.c net: core: rename indirect block ingress cb function 2019-12-06 20:45:09 -08:00
gen_estimator.c net_sched: gen_estimator: extend packet counter to 64bit 2019-11-06 21:51:36 -08:00
gen_stats.c net_sched: add TCA_STATS_PKT64 attribute 2019-11-05 18:20:55 -08:00
gro_cells.c gro_cells: make sure device is up in gro_cells_receive() 2019-03-10 11:07:14 -07:00
hwbm.c net: hwbm: Make the hwbm_pool lock a mutex 2019-06-09 19:40:10 -07:00
link_watch.c net: link_watch: prevent starvation when processing linkwatch wq 2019-07-01 19:02:47 -07:00
lwt_bpf.c net: ipv6_stub: use ip6_dst_lookup_flow instead of ip6_dst_lookup 2019-12-04 12:27:13 -08:00
lwtunnel.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
Makefile bpf: Introduce bpf sk local storage 2019-04-27 09:07:04 -07:00
neighbour.c net: add annotations on hh->hh_len lockless accesses 2019-11-07 20:07:30 -08:00
net-procfs.c net: procfs: use index hashlist instead of name hashlist 2019-10-01 14:47:19 -07:00
net-sysfs.c net-sysfs: Call dev_hold always in netdev_queue_add_kobject 2019-12-06 20:37:28 -08:00
net-sysfs.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
net-traces.c page_pool: add tracepoints for page_pool with details need by XDP 2019-06-19 11:23:13 -04:00
net_namespace.c netns: fix GFP flags in rtnl_net_notifyid() 2019-10-25 20:14:42 -07:00
netclassid_cgroup.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
netevent.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
netpoll.c net: fix skb use after free in netpoll 2019-08-27 20:52:02 -07:00
netprio_cgroup.c netprio: use css ID instead of cgroup ID 2019-11-12 08:18:03 -08:00
page_pool.c net: page_pool: add the possibility to sync DMA memory for device 2019-11-20 12:34:28 -08:00
pktgen.c pktgen: remove unnecessary assignment in pktgen_xmit() 2019-10-17 14:25:13 -04:00
ptp_classifier.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 295 2019-06-05 17:36:38 +02:00
request_sock.c tcp: add rcu protection around tp->fastopen_rsk 2019-10-13 10:13:08 -07:00
rtnetlink.c net/core: Populate VF index in struct ifla_vf_guid 2019-12-03 11:24:34 -08:00
scm.c y2038: socket: remove timespec reference in timestamping 2019-11-15 14:38:29 +01:00
secure_seq.c treewide: Add SPDX license identifier for missed files 2019-05-21 10:50:45 +02:00
skbuff.c net: Fixed updating of ethertype in skb_mpls_push() 2019-12-04 17:11:25 -08:00
skmsg.c net: skmsg: fix TLS 1.3 crash with full sk_msg 2019-11-28 22:40:29 -08:00
sock.c Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-11-26 16:02:40 -08:00
sock_diag.c sock: make cookie generation global instead of per netns 2019-08-09 13:14:46 -07:00
sock_map.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-09-15 14:17:27 +02:00
sock_reuseport.c net/core: Replace rcu_swap_protected() with rcu_replace_pointer() 2019-10-30 08:45:26 -07:00
stream.c tcp: make sure EPOLLOUT wont be missed 2019-08-19 13:07:43 -07:00
sysctl_net_core.c net: use listified RX for handling GRO_NORMAL skbs 2019-08-08 18:22:29 -07:00
timestamping.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 61 2019-05-24 17:36:45 +02:00
tso.c net: Use skb accessors in network core 2019-07-22 20:47:56 -07:00
utils.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
xdp.c xdp: obtain the mem_id mutex before trying to remove an entry. 2019-12-04 16:35:18 -08:00