0da2dbd602
the following script:
# tc qdisc add dev crash0 clsact
# tc filter add dev crash0 egress matchall \
> action gact pass index 90
# tc actions replace action gact \
> goto chain 42 index 90 cookie c1a0c1a0
# tc actions show action gact
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: gact action goto chain 42
random type none pass val 0
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 0 P4D 0
Oops: 0000 [#1] SMP PTI
CPU: 2 PID: 0 Comm: swapper/2 Not tainted 5.0.0-rc4.gotochain_crash+ #533
Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
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:ffff8c2434703be0 EFLAGS: 00010246
RAX: 000000002000002a RBX: ffff8c23ed6d7e00 RCX: 000000000000005a
RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff8c23ed6d7e00
RBP: ffff8c2434703c80 R08: ffff8c243b639ac8 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8c2429e68b00
R13: ffff8c2429e68b08 R14: 0000000000000001 R15: ffff8c2429c5a480
FS: 0000000000000000(0000) GS:ffff8c2434700000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000002dc0e005 CR4: 00000000001606e0
Call Trace:
<IRQ>
tcf_classify+0x58/0x120
__dev_queue_xmit+0x40a/0x890
? ip6_finish_output2+0x369/0x590
ip6_finish_output2+0x369/0x590
? ip6_output+0x68/0x110
ip6_output+0x68/0x110
? nf_hook.constprop.35+0x79/0xc0
mld_sendpack+0x16f/0x220
mld_ifc_timer_expire+0x195/0x2c0
? igmp6_timer_handler+0x70/0x70
call_timer_fn+0x2b/0x130
run_timer_softirq+0x3e8/0x440
? tick_sched_timer+0x37/0x70
__do_softirq+0xe3/0x2f5
irq_exit+0xf0/0x100
smp_apic_timer_interrupt+0x6c/0x130
apic_timer_interrupt+0xf/0x20
</IRQ>
RIP: 0010:native_safe_halt+0x2/0x10
Code: 74 ff ff ff 7f f3 c3 65 48 8b 04 25 00 5c 01 00 f0 80 48 02 20 48 8b 00 a8 08 74 8b eb c1 90 90 90 90 90 90 90 90 90 90 fb f4 <c3> 0f 1f 00 66 2e 0f 1f 84 00 00 00 00 00 f4 c3 90 90 90 90 90 90
RSP: 0018:ffff9c8640387eb8 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: ffffffff8b2184f0 RBX: 0000000000000002 RCX: 0000000000000001
RDX: 0000000000000001 RSI: 0000000000000087 RDI: 0000000000000002
RBP: 0000000000000002 R08: 000eb57882b36cc3 R09: 0000000000000020
R10: 0000000000000004 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
? __sched_text_end+0x1/0x1
default_idle+0x1c/0x140
do_idle+0x1c4/0x280
cpu_startup_entry+0x19/0x20
start_secondary+0x1a7/0x200
secondary_startup_64+0xa4/0xb0
Modules linked in: act_gact act_bpf veth ip6table_filter ip6_tables iptable_filter binfmt_misc crct10dif_pclmul crc32_pclmul ghash_clmulni_intel snd_hda_codec_generic ext4 snd_hda_intel snd_hda_codec snd_hwdep snd_hda_core mbcache jbd2 snd_seq snd_seq_device snd_pcm aesni_intel crypto_simd cryptd glue_helper virtio_balloon joydev pcspkr snd_timer snd i2c_piix4 soundcore nfsd auth_rpcgss nfs_acl lockd grace sunrpc ip_tables xfs ata_generic pata_acpi qxl drm_kms_helper syscopyarea virtio_net sysfillrect net_failover virtio_blk sysimgblt fb_sys_fops virtio_console ttm failover drm crc32c_intel serio_raw ata_piix libata floppy virtio_pci virtio_ring virtio dm_mirror dm_region_hash dm_log dm_mod [last unloaded: act_bpf]
CR2: 0000000000000000
Validating the control action within tcf_gact_init() proved to fix the
above issue. A TDC selftest is added to verify the correct behavior.
Fixes: db50514f9a9c ("net: sched: add termination action to allow goto chain")
Fixes: 97763dc0f401 ("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.