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Eyal Birger b02d196c44 bpf, lwt: Fix crash when using bpf_skb_set_tunnel_key() from bpf_xmit lwt hook 
xmit_check_hhlen() observes the dst for getting the device hard header
length to make sure a modified packet can fit. When a helper which changes
the dst - such as bpf_skb_set_tunnel_key() - is called as part of the
xmit program the accessed dst is no longer valid.

This leads to the following splat:

 BUG: kernel NULL pointer dereference, address: 00000000000000de
 #PF: supervisor read access in kernel mode
 #PF: error_code(0x0000) - not-present page
 PGD 0 P4D 0
 Oops: 0000 [#1] PREEMPT SMP PTI
 CPU: 0 PID: 798 Comm: ping Not tainted 5.18.0-rc2+ #103
 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014
 RIP: 0010:bpf_xmit+0xfb/0x17f
 Code: c6 c0 4d cd 8e 48 c7 c7 7d 33 f0 8e e8 42 09 fb ff 48 8b 45 58 48 8b 95 c8 00 00 00 48 2b 95 c0 00 00 00 48 83 e0 fe 48 8b 00 <0f> b7 80 de 00 00 00 39 c2 73 22 29 d0 b9 20 0a 00 00 31 d2 48 89
 RSP: 0018:ffffb148c0bc7b98 EFLAGS: 00010282
 RAX: 0000000000000000 RBX: 0000000000240008 RCX: 0000000000000000
 RDX: 0000000000000010 RSI: 00000000ffffffea RDI: 00000000ffffffff
 RBP: ffff922a828a4e00 R08: ffffffff8f1350e8 R09: 00000000ffffdfff
 R10: ffffffff8f055100 R11: ffffffff8f105100 R12: 0000000000000000
 R13: ffff922a828a4e00 R14: 0000000000000040 R15: 0000000000000000
 FS:  00007f414e8f0080(0000) GS:ffff922afdc00000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 00000000000000de CR3: 0000000002d80006 CR4: 0000000000370ef0
 Call Trace:
  <TASK>
  lwtunnel_xmit.cold+0x71/0xc8
  ip_finish_output2+0x279/0x520
  ? __ip_finish_output.part.0+0x21/0x130

Fix by fetching the device hard header length before running the BPF code.

Fixes: 3a0af8fd61f9 ("bpf: BPF for lightweight tunnel infrastructure")
Signed-off-by: Eyal Birger <eyal.birger@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220420165219.1755407-1-eyal.birger@gmail.com
2022-04-22 17:45:25 +02:00
..
bpf_sk_storage.c
bpf: Check for NULL return from bpf_get_btf_vmlinux
2022-03-20 19:21:38 -07:00
datagram.c
net: avoid double accounting for pure zerocopy skbs
2021-11-03 11:19:49 +00:00
datagram.h
…
dev_addr_lists_test.c
net: kunit: add a test for dev_addr_lists
2021-11-20 12:25:57 +00:00
dev_addr_lists.c
dev_addr_list: put the first addr on the tree
2021-11-20 12:25:57 +00:00
dev_ioctl.c
net_tstamp: add new flag HWTSTAMP_FLAG_BONDED_PHC_INDEX
2021-12-14 12:28:24 +00:00
dev.c
net: move net_unlink_todo() out of the header
2022-03-28 14:40:08 -07:00
devlink.c
devlink: hold the instance lock during eswitch_mode callbacks
2022-03-21 14:11:38 +00:00
drop_monitor.c
drop_monitor: remove quadratic behavior
2022-02-23 12:39:58 +00:00
dst_cache.c
wireguard: device: reset peer src endpoint when netns exits
2021-11-29 19:50:45 -08:00
dst.c
net: dst: add net device refcount tracking to dst_entry
2021-12-06 16:05:10 -08:00
failover.c
net: failover: add net device refcount tracker
2021-12-06 16:06:02 -08:00
fib_notifier.c
…
fib_rules.c
fib: expand fib_rule_policy
2021-12-16 07:18:35 -08:00
filter.c
bpf: Support dual-stack sockets in bpf_tcp_check_syncookie
2022-04-06 09:44:45 -07:00
flow_dissector.c
flow_dissector: Add support for HSRv0
2022-03-11 11:05:52 +00:00
flow_offload.c
flow_offload: add reoffload process to update hw_count
2021-12-19 14:08:48 +00:00
gen_estimator.c
net: sched: Remove Qdisc::running sequence counter
2021-10-18 12:54:41 +01:00
gen_stats.c
net: stats: Read the statistics in ___gnet_stats_copy_basic() instead of adding.
2021-10-21 12:47:56 +01:00
gro_cells.c
net: add per-cpu storage and net->core_stats
2022-03-11 23:17:24 -08:00
gro.c
Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
2022-03-10 17:16:56 -08:00
hwbm.c
…
link_watch.c
net: refine dev_put()/dev_hold() debugging
2022-02-05 15:22:45 +00:00
lwt_bpf.c
bpf, lwt: Fix crash when using bpf_skb_set_tunnel_key() from bpf_xmit lwt hook
2022-04-22 17:45:25 +02:00
lwtunnel.c
lwtunnel: Validate RTA_ENCAP_TYPE attribute length
2021-12-31 14:31:59 +00:00
Makefile
net: kunit: add a test for dev_addr_lists
2021-11-20 12:25:57 +00:00
neighbour.c
net: neigh: use kfree_skb_reason() for __neigh_event_send()
2022-02-26 12:53:59 +00:00
net_namespace.c
net: initialize init_net earlier
2022-02-06 11:04:29 +00:00
net-procfs.c
net-procfs: show net devices bound packet types
2022-01-24 11:58:46 +00:00
net-sysfs.c
Linux 5.17-rc8
2022-03-15 10:28:12 +01:00
net-sysfs.h
…
net-traces.c
tcp: add tracepoint for checksum errors
2021-05-14 15:26:03 -07:00
netclassid_cgroup.c
bpf, cgroups: Fix cgroup v2 fallback on v1/v2 mixed mode
2021-09-13 16:35:58 -07:00
netevent.c
net: core: Correct function name netevent_unregister_notifier() in the kerneldoc
2021-03-28 17:56:56 -07:00
netpoll.c
netpoll: add net device refcount tracker to struct netpoll
2021-12-06 16:06:02 -08:00
netprio_cgroup.c
bpf, cgroups: Fix cgroup v2 fallback on v1/v2 mixed mode
2021-09-13 16:35:58 -07:00
of_net.c
Revert "of: net: support NVMEM cells with MAC in text format"
2022-01-12 14:14:36 +00:00
page_pool.c
page_pool: Add function to batch and return stats
2022-03-03 09:55:28 +00:00
pktgen.c
proc: remove PDE_DATA() completely
2022-01-22 08:33:37 +02:00
ptp_classifier.c
ptp: Add generic PTP is_sync() function
2022-03-07 11:31:34 +00:00
request_sock.c
…
rtnetlink.c
net: limit altnames to 64k total
2022-03-10 20:15:23 -08:00
scm.c
memcg: enable accounting for scm_fp_list objects
2021-07-20 06:00:38 -07:00
secure_seq.c
net: align static siphash keys
2021-11-16 19:07:54 -08:00
selftests.c
net: core: constify mac addrs in selftests
2021-10-24 13:59:44 +01:00
skbuff.c
skbuff: fix coalescing for page_pool fragment recycling
2022-04-01 11:57:58 +01:00
skmsg.c
bpf, sockmap: Fix memleak in tcp_bpf_sendmsg while sk msg is full
2022-03-15 16:43:31 +01:00
sock_destructor.h
skb_expand_head() adjust skb->truesize incorrectly
2021-10-22 12:35:51 -07:00
sock_diag.c
net: Don't include filter.h from net/sock.h
2021-12-29 08:48:14 -08:00
sock_map.c
bpf: support BPF_PROG_QUERY for progs attached to sockmap
2022-01-20 21:30:58 -08:00
sock_reuseport.c
tcp: Add stats for socket migration.
2021-06-23 12:56:08 -07:00
sock.c
SO_ZEROCOPY should return -EOPNOTSUPP rather than -ENOTSUPP
2022-03-08 22:14:49 -08:00
stream.c
net: stream: don't purge sk_error_queue in sk_stream_kill_queues()
2021-10-16 09:06:09 +01:00
sysctl_net_core.c
net/sysctl: avoid two synchronize_rcu() calls
2022-02-28 11:40:47 +00:00
timestamping.c
…
tso.c
net: tso: add UDP segmentation support
2020-06-18 20:46:23 -07:00
utils.c
net: core: Use csum_replace_by_diff() and csum_sub() instead of opencoding
2022-02-21 11:40:44 +00:00
xdp.c
Merge https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
2022-03-22 11:18:49 -07:00