• Davide Caratti's avatar
    net/sched: act_gact: validate the control action inside init() · 0da2dbd6
    Davide Caratti authored
    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: db50514f ("net: sched: add termination action to allow goto chain")
    Fixes: 97763dc0 ("net_sched: reject unknown tcfa_action values")
    Signed-off-by: default avatarDavide Caratti <dcaratti@redhat.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    0da2dbd6
act_gact.c 7.82 KB