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e8c87c643e
the following script:
# tc qdisc add dev crash0 clsact
# tc filter add dev crash0 egress matchall \
> action sample rate 1024 group 4 pass index 90
# tc actions replace action sample \
> rate 1024 group 4 goto chain 42 index 90 cookie c1a0c1a0
# tc actions show action sample
had the following output:
Error: Failed to init TC action chain.
We have an error talking to the kernel
total acts 1
action order 0: sample rate 1/1024 group 4 goto chain 42
index 90 ref 2 bind 1
cookie c1a0c1a0
Then, the first packet transmitted by crash0 made the kernel crash:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
#PF error: [normal kernel read fault]
PGD 8000000079966067 P4D 8000000079966067 PUD 7987b067 PMD 0
Oops: 0000 [#1] SMP PTI
CPU: 0 PID: 5 Comm: kworker/0:0 Not tainted 5.0.0-rc4.gotochain_crash+ #536
Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
Workqueue: ipv6_addrconf addrconf_dad_work
RIP: 0010:tcf_action_exec+0xb8/0x100
Code: 00 00 00 20 74 1d 83 f8 03 75 09 49 83 c4 08 4d 39 ec 75 bc 48 83 c4 10 5b 5d 41 5c 41 5d 41 5e 41 5f c3 49 8b 97 a8 00 00 00 <48> 8b 12 48 89 55 00 48 83 c4 10 5b 5d 41 5c 41 5d 41 5e 41 5f c3
RSP: 0018:ffffbee60033fad0 EFLAGS: 00010246
RAX: 000000002000002a RBX: ffff99d7ae6e3b00 RCX: 00000000e555df9b
RDX: 0000000000000000 RSI: 00000000b0352718 RDI: ffff99d7fda1fcf0
RBP: ffffbee60033fb70 R08: 0000000070731ab1 R09: 0000000000000400
R10: 0000000000000000 R11: ffff99d7ac733838 R12: ffff99d7f3c2be00
R13: ffff99d7f3c2be08 R14: 0000000000000001 R15: ffff99d7f3c2b600
FS: 0000000000000000(0000) GS:ffff99d7fda00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 00000000797de006 CR4: 00000000001606f0
Call Trace:
tcf_classify+0x58/0x120
__dev_queue_xmit+0x40a/0x890
? ndisc_next_option+0x50/0x50
? ___neigh_create+0x4d5/0x680
? ip6_finish_output2+0x1b5/0x590
ip6_finish_output2+0x1b5/0x590
? ip6_output+0x68/0x110
ip6_output+0x68/0x110
? nf_hook.constprop.28+0x79/0xc0
ndisc_send_skb+0x248/0x2e0
ndisc_send_ns+0xf8/0x200
? addrconf_dad_work+0x389/0x4b0
addrconf_dad_work+0x389/0x4b0
? __switch_to_asm+0x34/0x70
? process_one_work+0x195/0x380
? addrconf_dad_completed+0x370/0x370
process_one_work+0x195/0x380
worker_thread+0x30/0x390
? process_one_work+0x380/0x380
kthread+0x113/0x130
? kthread_park+0x90/0x90
ret_from_fork+0x35/0x40
Modules linked in: act_sample psample veth ip6table_filter ip6_tables iptable_filter binfmt_misc ext4 crct10dif_pclmul crc32_pclmul ghash_clmulni_intel mbcache jbd2 snd_hda_codec_generic snd_hda_intel snd_hda_codec snd_hwdep snd_hda_core snd_seq snd_seq_device aesni_intel crypto_simd snd_pcm cryptd glue_helper snd_timer joydev snd pcspkr virtio_balloon i2c_piix4 soundcore nfsd auth_rpcgss nfs_acl lockd grace sunrpc ip_tables xfs ata_generic pata_acpi qxl drm_kms_helper syscopyarea sysfillrect virtio_net sysimgblt fb_sys_fops net_failover ttm failover virtio_blk virtio_console drm ata_piix serio_raw crc32c_intel libata virtio_pci virtio_ring virtio floppy dm_mirror dm_region_hash dm_log dm_mod
CR2: 0000000000000000
Validating the control action within tcf_sample_init() proved to fix the
above issue. A TDC selftest is added to verify the correct behavior.
Fixes: db50514f9a ("net: sched: add termination action to allow goto chain")
Fixes: 97763dc0f4 ("net_sched: reject unknown tcfa_action values")
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.