On Wed 27 Feb 2019 at 17:40, Davide Caratti <dcara...@redhat.com> wrote:
> the following script:
>
> # tc qdisc add dev crash0 clsact
> # tc filter add dev crash0 egress matchall \
> > action connmark pass index 90
> # tc actions replace action connmark \
> > goto chain 42 index 90 cookie c1a0c1a0
> # tc actions show action connmark
>
> 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: connmark zone 0 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 0 P4D 0
> Oops: 0000 [#1] SMP PTI
> CPU: 0 PID: 302 Comm: kworker/0:2 Not tainted 5.0.0-rc4.gotochain_crash+ #533
> 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:ffff9bea406c3ad0 EFLAGS: 00010246
> RAX: 000000002000002a RBX: ffff8c5dfc009f00 RCX: 0000000000000000
> RDX: 0000000000000000 RSI: ffff9bea406c3a80 RDI: ffff8c5dfb9d6ec0
> RBP: ffff9bea406c3b70 R08: ffff8c5dfda222a0 R09: ffffffff90933c3c
> R10: 0000000000000000 R11: 0000000092793f7d R12: ffff8c5df48b3c00
> R13: ffff8c5df48b3c08 R14: 0000000000000001 R15: ffff8c5dfb9d6e40
> FS: 0000000000000000(0000) GS:ffff8c5dfda00000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000000000 CR3: 0000000062e0e006 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_connmark nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4
> veth ip6table_filter ip6_tables iptable_filter binfmt_misc ext4
> crct10dif_pclmul mbcache crc32_pclmul jbd2 snd_hda_codec_generic
> ghash_clmulni_intel snd_hda_intel snd_hda_codec snd_hwdep snd_hda_core
> snd_seq snd_seq_device snd_pcm aesni_intel snd_timer crypto_simd cryptd snd
> glue_helper joydev virtio_balloon pcspkr soundcore i2c_piix4 nfsd auth_rpcgss
> nfs_acl lockd grace sunrpc ip_tables xfs ata_generic pata_acpi qxl
> drm_kms_helper virtio_net net_failover syscopyarea virtio_blk failover
> virtio_console sysfillrect sysimgblt fb_sys_fops ttm drm ata_piix
> crc32c_intel serio_raw libata virtio_pci virtio_ring virtio floppy dm_mirror
> dm_region_hash dm_log dm_mod
> CR2: 0000000000000000
>
> Validating the control action within tcf_connmark_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 <dcara...@redhat.com>
> ---
> net/sched/act_connmark.c | 24 +++++++++++++++++-
> .../tc-testing/tc-tests/actions/connmark.json | 25 +++++++++++++++++++
> 2 files changed, 48 insertions(+), 1 deletion(-)
>
> diff --git a/net/sched/act_connmark.c b/net/sched/act_connmark.c
> index 30c4c109c80c..5e02f9f6850a 100644
> --- a/net/sched/act_connmark.c
> +++ b/net/sched/act_connmark.c
> @@ -21,6 +21,7 @@
> #include <net/netlink.h>
> #include <net/pkt_sched.h>
> #include <net/act_api.h>
> +#include <net/pkt_cls.h>
> #include <uapi/linux/tc_act/tc_connmark.h>
> #include <net/tc_act/tc_connmark.h>
>
> @@ -101,10 +102,11 @@ static int tcf_connmark_init(struct net *net, struct
> nlattr *nla,
> struct netlink_ext_ack *extack)
> {
> struct tc_action_net *tn = net_generic(net, connmark_net_id);
> + struct tcf_chain *newchain = NULL, *oldchain;
> struct nlattr *tb[TCA_CONNMARK_MAX + 1];
> struct tcf_connmark_info *ci;
> struct tc_connmark *parm;
> - int ret = 0;
> + int ret = 0, err;
>
> if (!nla)
> return -EINVAL;
> @@ -129,6 +131,12 @@ static int tcf_connmark_init(struct net *net, struct
> nlattr *nla,
> }
>
> ci = to_connmark(*a);
> + err = tcf_action_check_ctrlact(parm->action, tp, &newchain,
> + extack);
> + if (err)
> + goto release_idr;
> + oldchain = ci->tcf_goto_chain;
> + ci->tcf_goto_chain = newchain;
> ci->tcf_action = parm->action;
> ci->net = net;
> ci->zone = parm->zone;
> @@ -143,15 +151,29 @@ static int tcf_connmark_init(struct net *net, struct
> nlattr *nla,
> tcf_idr_release(*a, bind);
> return -EEXIST;
> }
> + err = tcf_action_check_ctrlact(parm->action, tp, &newchain,
> + extack);
> + if (err)
> + goto release_idr;
> /* replacing action and zone */
> spin_lock_bh(&ci->tcf_lock);
> + oldchain = ci->tcf_goto_chain;
> + ci->tcf_goto_chain = newchain;
> ci->tcf_action = parm->action;
> ci->zone = parm->zone;
> spin_unlock_bh(&ci->tcf_lock);
> ret = 0;
> + } else {
> + goto end;
Maybe just initialize oldchain to NULL to avoid this goto?
> }
>
> + if (oldchain)
> + tcf_chain_put_by_act(oldchain);
> +end:
> return ret;
> +release_idr:
> + tcf_idr_release(*a, bind);
> + return err;
> }
>
> static inline int tcf_connmark_dump(struct sk_buff *skb, struct tc_action *a,
> diff --git
> a/tools/testing/selftests/tc-testing/tc-tests/actions/connmark.json
> b/tools/testing/selftests/tc-testing/tc-tests/actions/connmark.json
> index 13147a1f5731..cadde8f41fcd 100644
> --- a/tools/testing/selftests/tc-testing/tc-tests/actions/connmark.json
> +++ b/tools/testing/selftests/tc-testing/tc-tests/actions/connmark.json
> @@ -287,5 +287,30 @@
> "teardown": [
> "$TC actions flush action connmark"
> ]
> + },
> + {
> + "id": "c506",
> + "name": "Replace connmark with invalid goto chain control",
> + "category": [
> + "actions",
> + "connmark"
> + ],
> + "setup": [
> + [
> + "$TC actions flush action connmark",
> + 0,
> + 1,
> + 255
> + ],
> + "$TC actions add action connmark pass index 90"
> + ],
> + "cmdUnderTest": "$TC actions replace action connmark goto chain 42
> index 90 cookie c1a0c1a0",
> + "expExitCode": "255",
> + "verifyCmd": "$TC actions get action connmark index 90",
> + "matchPattern": "action order [0-9]+: connmark zone 0 pass.*index 90
> ref",
> + "matchCount": "1",
> + "teardown": [
> + "$TC actions flush action connmark"
> + ]
> }
> ]
