linux/net
Neil Horman 6071bd1aa1 netem: Segment GSO packets on enqueue
This was recently reported to me, and reproduced on the latest net kernel,
when attempting to run netperf from a host that had a netem qdisc attached
to the egress interface:

[  788.073771] ---------------------[ cut here ]---------------------------
[  788.096716] WARNING: at net/core/dev.c:2253 skb_warn_bad_offload+0xcd/0xda()
[  788.129521] bnx2: caps=(0x00000001801949b3, 0x0000000000000000) len=2962
data_len=0 gso_size=1448 gso_type=1 ip_summed=3
[  788.182150] Modules linked in: sch_netem kvm_amd kvm crc32_pclmul ipmi_ssif
ghash_clmulni_intel sp5100_tco amd64_edac_mod aesni_intel lrw gf128mul
glue_helper ablk_helper edac_mce_amd cryptd pcspkr sg edac_core hpilo ipmi_si
i2c_piix4 k10temp fam15h_power hpwdt ipmi_msghandler shpchp acpi_power_meter
pcc_cpufreq nfsd auth_rpcgss nfs_acl lockd grace sunrpc ip_tables xfs libcrc32c
sd_mod crc_t10dif crct10dif_generic mgag200 syscopyarea sysfillrect sysimgblt
i2c_algo_bit drm_kms_helper ahci ata_generic pata_acpi ttm libahci
crct10dif_pclmul pata_atiixp tg3 libata crct10dif_common drm crc32c_intel ptp
serio_raw bnx2 r8169 hpsa pps_core i2c_core mii dm_mirror dm_region_hash dm_log
dm_mod
[  788.465294] CPU: 16 PID: 0 Comm: swapper/16 Tainted: G        W
------------   3.10.0-327.el7.x86_64 #1
[  788.511521] Hardware name: HP ProLiant DL385p Gen8, BIOS A28 12/17/2012
[  788.542260]  ffff880437c036b8 f7afc56532a53db9 ffff880437c03670
ffffffff816351f1
[  788.576332]  ffff880437c036a8 ffffffff8107b200 ffff880633e74200
ffff880231674000
[  788.611943]  0000000000000001 0000000000000003 0000000000000000
ffff880437c03710
[  788.647241] Call Trace:
[  788.658817]  <IRQ>  [<ffffffff816351f1>] dump_stack+0x19/0x1b
[  788.686193]  [<ffffffff8107b200>] warn_slowpath_common+0x70/0xb0
[  788.713803]  [<ffffffff8107b29c>] warn_slowpath_fmt+0x5c/0x80
[  788.741314]  [<ffffffff812f92f3>] ? ___ratelimit+0x93/0x100
[  788.767018]  [<ffffffff81637f49>] skb_warn_bad_offload+0xcd/0xda
[  788.796117]  [<ffffffff8152950c>] skb_checksum_help+0x17c/0x190
[  788.823392]  [<ffffffffa01463a1>] netem_enqueue+0x741/0x7c0 [sch_netem]
[  788.854487]  [<ffffffff8152cb58>] dev_queue_xmit+0x2a8/0x570
[  788.880870]  [<ffffffff8156ae1d>] ip_finish_output+0x53d/0x7d0
...

The problem occurs because netem is not prepared to handle GSO packets (as it
uses skb_checksum_help in its enqueue path, which cannot manipulate these
frames).

The solution I think is to simply segment the skb in a simmilar fashion to the
way we do in __dev_queue_xmit (via validate_xmit_skb), with some minor changes.
When we decide to corrupt an skb, if the frame is GSO, we segment it, corrupt
the first segment, and enqueue the remaining ones.

tested successfully by myself on the latest net kernel, to which this applies

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
CC: Jamal Hadi Salim <jhs@mojatatu.com>
CC: "David S. Miller" <davem@davemloft.net>
CC: netem@lists.linux-foundation.org
CC: eric.dumazet@gmail.com
CC: stephen@networkplumber.org
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-05-03 00:33:14 -04:00
..
6lowpan 6lowpan: iphc: fix SAM/DAM bit comment 2016-03-10 19:51:29 +01:00
9p net/9p: convert to new CQ API 2016-03-10 20:54:09 -05:00
802
8021q vlan: propagate gso_max_segs 2016-03-17 21:05:01 -04:00
appletalk appletalk: fix erroneous return value 2016-02-18 14:59:34 -05:00
atm net: Generalise wq_has_sleeper helper 2015-11-30 14:47:33 -05:00
ax25 ax25: add link layer header validation function 2016-03-09 22:13:01 -05:00
batman-adv batman-adv: Fix reference counting of hardif_neigh_node object for neigh_node 2016-04-29 19:46:11 +08:00
bluetooth Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2016-03-19 10:05:34 -07:00
bridge bridge: mdb: Marking port-group as offloaded 2016-04-24 14:23:32 -04:00
caif net: caif: fix misleading indentation 2016-03-14 13:09:50 -04:00
can
ceph libceph: make authorizer destruction independent of ceph_auth_client 2016-04-25 20:54:13 +02:00
core vlan: pull on __vlan_insert_tag error path and fix csum correction 2016-04-15 23:20:11 -04:00
dcb
dccp tcp/dccp: remove obsolete WARN_ON() in icmp handlers 2016-03-17 21:06:40 -04:00
decnet decnet: Do not build routes to devices without decnet private data. 2016-04-10 23:01:30 -04:00
dns_resolver net: dns_resolver: convert time_t to time64_t 2015-11-18 16:27:46 -05:00
dsa net: dsa: refine netdev event notifier 2016-03-14 16:05:32 -04:00
ethernet eth: Pull header from first fragment via eth_get_headlen 2016-02-24 13:58:05 -05:00
hsr net/hsr: fix a warning message 2015-11-23 14:56:15 -05:00
ieee802154 ieee802154: 6lowpan: fix return of netdev notifier 2016-02-23 20:29:40 +01:00
ipv4 gre: do not pull header in ICMP error processing 2016-05-02 00:19:58 -04:00
ipv6 net: ipv6: Delete host routes on an ifdown 2016-04-26 11:48:26 -04:00
ipx
irda Merge 4.5-rc4 into tty-next 2016-02-14 14:36:04 -08:00
iucv af_iucv: Validate socket address length in iucv_sock_bind() 2016-01-19 14:21:08 -05:00
kcm kcm: Add receive message timeout 2016-03-09 16:36:15 -05:00
key
l2tp net: l2tp: fix reversed udp6 checksum flags 2016-05-01 19:32:16 -04:00
l3mdev net: l3mdev: address selection should only consider devices in L3 domain 2016-02-26 14:22:26 -05:00
lapb
llc af_llc: fix types on llc_ui_wait_for_conn 2016-02-17 16:12:13 -05:00
mac80211 mac80211: fix statistics leak if dev_alloc_name() fails 2016-04-27 10:06:58 +02:00
mac802154 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2016-03-19 10:05:34 -07:00
mpls mpls: find_outdev: check for err ptr in addition to NULL check 2016-04-08 12:43:20 -04:00
netfilter netfilter: nf_conntrack_tcp: Fix stack out of bounds when parsing TCP options 2016-04-07 18:42:37 +02:00
netlabel netlabel: do not initialise statics to NULL 2016-03-07 11:08:26 -05:00
netlink netlink: don't send NETLINK_URELEASE for unbound sockets 2016-04-10 23:32:23 -04:00
netrom
nfc Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2016-03-19 10:05:34 -07:00
openvswitch openvswitch: use flow protocol when recalculating ipv6 checksums 2016-04-21 15:28:47 -04:00
packet packet: fix heap info leak in PACKET_DIAG_MCLIST sock_diag interface 2016-04-14 00:46:39 -04:00
phonet sock: struct proto hash function may error 2016-02-11 03:54:14 -05:00
rds RDS: Fix the atomicity for congestion map update 2016-04-16 19:01:05 -04:00
rfkill Here's another round of updates for -next: 2016-03-01 17:03:27 -05:00
rose
rxrpc Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2016-03-19 10:05:34 -07:00
sched netem: Segment GSO packets on enqueue 2016-05-03 00:33:14 -04:00
sctp sctp: avoid refreshing heartbeat timer too often 2016-04-10 22:22:34 -04:00
sunrpc Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2016-04-14 18:15:40 -07:00
switchdev switchdev: Adding complete operation to deferred switchdev ops 2016-04-24 14:23:32 -04:00
tipc tipc: only process unicast on intended node 2016-05-01 21:03:30 -04:00
unix Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-02-23 00:09:14 -05:00
vmw_vsock VSOCK: Only check error on skb_recv_datagram when skb is NULL 2016-04-19 20:42:01 -04:00
wimax
wireless nl80211: check netlink protocol in socket release notification 2016-04-12 15:39:06 +02:00
x25
xfrm xfrm: Fix crash observed during device unregistration and decryption 2016-03-24 14:29:36 -04:00
compat.c
Kconfig Make DST_CACHE a silent config option 2016-03-21 22:56:38 -04:00
Makefile kcm: Kernel Connection Multiplexor module 2016-03-09 16:36:14 -05:00
socket.c net: Fix use after free in the recvmmsg exit path 2016-03-14 12:41:49 -04:00
sysctl_net.c