Subject: Re: [PATCH] bridge: reset IPCB in br_parse_ip_options

From: Scot Doyle <[email-masked]>
Date: Tue, 12 Apr 2011 23:12:34 -0500

On 04/12/2011 06:55 PM, Scot Doyle wrote:
> On 04/12/2011 12:18 PM, Eric Dumazet wrote:
>> Commit 462fb2af9788a82 (bridge : Sanitize skb before it enters the IP
>> stack), missed one IPCB init before calling ip_options_compile()
>>
>> Thanks to Scot Doyle for his tests and bug reports.
>>
>> Reported-by: Scot Doyle<[email-masked]>
>> Signed-off-by: Eric Dumazet<[email-masked]>
>> Cc: Hiroaki SHIMODA<[email-masked]>
>> Acked-by: Bandan Das<[email-masked]>
>> Acked-by: Stephen Hemminger<[email-masked]>
>> Cc: Jan Lübbe<[email-masked]>
>> ---
>> net/bridge/br_netfilter.c | 6 ++----
>> 1 file changed, 2 insertions(+), 4 deletions(-)
>>
>> diff --git a/net/bridge/br_netfilter.c b/net/bridge/br_netfilter.c
>> index 008ff6c..b353f7c 100644
>> --- a/net/bridge/br_netfilter.c
>> +++ b/net/bridge/br_netfilter.c
>> @@ -249,11 +249,9 @@ static int br_parse_ip_options(struct sk_buff *skb)
>> goto drop;
>> }
>>
>> - /* Zero out the CB buffer if no options present */
>> - if (iph->ihl == 5) {
>> - memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
>> + memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
>> + if (iph->ihl == 5)
>> return 0;
>> - }
>>
>> opt->optlen = iph->ihl*4 - sizeof(struct iphdr);
>> if (ip_options_compile(dev_net(dev), opt, skb))
>>
>>
>
>
> Here's the output after pulling 2.6.39-rc3, applying the patches listed
> below, doing a "make clean" and hitting the bridge's assigned ip address
> with the IP Stack Checker tcpsic command. Maybe I should also be
> applying the patch from yesterday too? I'll try that next.
>
> diff --git a/net/bridge/br_netfilter.c b/net/bridge/br_netfilter.c
> index 008ff6c..b9bdff9 100644
> --- a/net/bridge/br_netfilter.c
> +++ b/net/bridge/br_netfilter.c
> @@ -249,11 +249,9 @@ static int br_parse_ip_options(struct sk_buff *skb)
> goto drop;
> }
>
> - /* Zero out the CB buffer if no options present */
> - if (iph->ihl == 5) {
> - memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
> - return 0;
> - }
> + memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
> + if (iph->ihl == 5)
> + return 0;
>
> opt->optlen = iph->ihl*4 - sizeof(struct iphdr);
> if (ip_options_compile(dev_net(dev), opt, skb))
>
> diff --git a/net/ipv4/inetpeer.c b/net/ipv4/inetpeer.c
> index dd1b20e..9df4e63 100644
> --- a/net/ipv4/inetpeer.c
> +++ b/net/ipv4/inetpeer.c
> @@ -354,7 +354,8 @@ static void inetpeer_free_rcu(struct rcu_head *head)
> }
>
> /* May be called with local BH enabled. */
> -static void unlink_from_pool(struct inet_peer *p, struct inet_peer_base
> *base)
> +static void unlink_from_pool(struct inet_peer *p, struct inet_peer_base
> *base,
> + struct inet_peer __rcu **stack[PEER_MAXDEPTH])
> {
> int do_free;
>
> @@ -368,7 +369,6 @@ static void unlink_from_pool(struct inet_peer *p,
> struct inet_peer_base *base)
> * We use refcnt=-1 to alert lockless readers this entry is deleted.
> */
> if (atomic_cmpxchg(&p->refcnt, 1, -1) == 1) {
> - struct inet_peer __rcu **stack[PEER_MAXDEPTH];
> struct inet_peer __rcu ***stackptr, ***delp;
> if (lookup(&p->daddr, stack, base) != p)
> BUG();
> @@ -422,7 +422,7 @@ static struct inet_peer_base *peer_to_base(struct
> inet_peer *p)
> }
>
> /* May be called with local BH enabled. */
> -static int cleanup_once(unsigned long ttl)
> +static int cleanup_once(unsigned long ttl, struct inet_peer __rcu
> **stack[PEER_MAXDEPTH])
> {
> struct inet_peer *p = NULL;
>
> @@ -454,7 +454,7 @@ static int cleanup_once(unsigned long ttl)
> * happen because of entry limits in route cache. */
> return -1;
>
> - unlink_from_pool(p, peer_to_base(p));
> + unlink_from_pool(p, peer_to_base(p), stack);
> return 0;
> }
>
> @@ -524,7 +524,7 @@ struct inet_peer *inet_getpeer(struct inetpeer_addr
> *daddr, int create)
>
> if (base->total >= inet_peer_threshold)
> /* Remove one less-recently-used entry. */
> - cleanup_once(0);
> + cleanup_once(0, stack);
>
> return p;
> }
> @@ -540,6 +540,7 @@ static void peer_check_expire(unsigned long dummy)
> {
> unsigned long now = jiffies;
> int ttl, total;
> + struct inet_peer __rcu **stack[PEER_MAXDEPTH];
>
> total = compute_total();
> if (total >= inet_peer_threshold)
> @@ -548,7 +549,7 @@ static void peer_check_expire(unsigned long dummy)
> ttl = inet_peer_maxttl
> - (inet_peer_maxttl - inet_peer_minttl) / HZ *
> total / inet_peer_threshold * HZ;
> - while (!cleanup_once(ttl)) {
> + while (!cleanup_once(ttl, stack)) {
> if (jiffies != now)
> break;
> }
>
> diff --git a/net/ipv4/ip_options.c b/net/ipv4/ip_options.c
> index 28a736f..dea9947 100644
> --- a/net/ipv4/ip_options.c
> +++ b/net/ipv4/ip_options.c
> @@ -200,6 +200,11 @@ int ip_options_echo(struct ip_options * dopt,
> struct sk_buff * skb)
> *dptr++ = IPOPT_END;
> dopt->optlen++;
> }
> + if (unlikely(dopt->optlen > 40)) {
> + pr_err("ip_options_echo() fatal error optlen=%u > 40\n", dopt->optlen);
> + print_hex_dump(KERN_ERR, "ip options: ", DUMP_PREFIX_OFFSET,
> + 16, 1, dopt->__data, dopt->optlen, false);
> + }
> return 0;
> }
>
>
> ------------
>
>
> [ 761.720393] BUG: unable to handle kernel NULL pointer dereference at
> 00000000000000d0
> [ 761.728206] IP: [<ffffffff8129fbe9>] ip_options_compile+0x1c1/0x435
> [ 761.734452] PGD 0
> [ 761.736459] Oops: 0000 [#1] SMP
> [ 761.739683] last sysfs file: /sys/devices/virtual/misc/kvm/uevent
> [ 761.745744] CPU 0
> [ 761.747570] Modules linked in: kvm_intel kvm bridge stp loop snd_pcm
> snd_timer snd tpm_tis tpm tpm_bios soundcore psmouse snd_page_alloc
> processor ghes thermal_sys
> i7core_edac evdev pcspkr serio_raw edac_core dcdbas power_meter button
> hed ext2 mbcache dm_mod raid1 md_mod sd_mod crc_t10dif usb_storage uas
> uhci_hcd ehci_hcd mpt2sas
> scsi_transport_sas raid_class igb scsi_mod usbcore bnx2 dca [last
> unloaded: scsi_wait_scan]
> [ 761.785171]
> [ 761.786651] Pid: 0, comm: swapper Not tainted 2.6.39-rc3+ #14 Dell
> Inc. PowerEdge R510/0DPRKF
> [ 761.795157] RIP: 0010:[<ffffffff8129fbe9>] [<ffffffff8129fbe9>]
> ip_options_compile+0x1c1/0x435
> [ 761.803823] RSP: 0018:ffff88042f203af0 EFLAGS: 00010286
> [ 761.809106] RAX: 0000000000000017 RBX: ffff8804027b3600 RCX:
> ffff88040466a864
> [ 761.816205] RDX: 000000000000001a RSI: 0000000000000000 RDI:
> ffffffff817e6100
> [ 761.823304] RBP: ffff88040466a862 R08: ffffffffa01d6e89 R09:
> ffff88042f203c58
> [ 761.830402] R10: 0000000000000000 R11: 0000000000000000 R12:
> ffff8804027b3628
> [ 761.837501] R13: 000000000000001d R14: ffff88040466a84e R15:
> 0000000000000024
> [ 761.844601] FS: 0000000000000000(0000) GS:ffff88042f200000(0000)
> knlGS:0000000000000000
> [ 761.852650] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
> [ 761.858365] CR2: 00000000000000d0 CR3: 0000000001603000 CR4:
> 00000000000006f0
> [ 761.865463] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
> 0000000000000000
> [ 761.872562] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7:
> 0000000000000400
> [ 761.879661] Process swapper (pid: 0, threadinfo ffffffff81600000, task
> ffffffff8160b020)
> [ 761.887710] Stack:
> [ 761.889708] 0000000000000000 ffffffff81276928 0000000000000000
> ffffffff817e6100
> [ 761.897102] 000000000000004e ffff88040500e600 ffff88040500e600
> ffff8804027b3600
> [ 761.904496] ffff880404fc0000 ffff8804027b3628 0000000000000000
> ffff880404fc0000
> [ 761.911889] Call Trace:
> [ 761.914319] <IRQ>
> [ 761.916413] [<ffffffff81276928>] ? netif_receive_skb+0x52/0x58
> [ 761.922306] [<ffffffffa01dae3b>] ? br_parse_ip_options+0x134/0x1a8
> [bridge]
> [ 761.929319] [<ffffffffa01dbbe0>] ? br_nf_pre_routing+0x348/0x3cb [bridge]
> [ 761.936160] [<ffffffff81298527>] ? nf_iterate+0x41/0x7e
> [ 761.941444] [<ffffffff8104afaa>] ? irq_exit+0x58/0x8f
> [ 761.946556] [<ffffffffa01d6e89>] ? NF_HOOK.clone.4+0x56/0x56 [bridge]
> [ 761.953052] [<ffffffffa01d6e89>] ? NF_HOOK.clone.4+0x56/0x56 [bridge]
> [ 761.959546] [<ffffffff812985d7>] ? nf_hook_slow+0x73/0x114
> [ 761.965089] [<ffffffffa01d6e89>] ? NF_HOOK.clone.4+0x56/0x56 [bridge]
> [ 761.971583] [<ffffffff8126d097>] ? __netdev_alloc_skb+0x15/0x2f
> [ 761.977561] [<ffffffffa01d6e89>] ? NF_HOOK.clone.4+0x56/0x56 [bridge]
> [ 761.984055] [<ffffffffa01d6e6f>] ? NF_HOOK.clone.4+0x3c/0x56 [bridge]
> [ 761.990551] [<ffffffff812a7dde>] ? tcp_gro_receive+0xa1/0x204
> [ 761.996355] [<ffffffffa01d71e5>] ? br_handle_frame+0x195/0x1ac [bridge]
> [ 762.003022] [<ffffffffa01d7050>] ? br_handle_frame_finish+0x1c7/0x1c7
> [bridge]
> [ 762.010294] [<ffffffff812764ef>] ? __netif_receive_skb+0x2a7/0x450
> [ 762.016530] [<ffffffff81276928>] ? netif_receive_skb+0x52/0x58
> [ 762.022420] [<ffffffff81276e2a>] ? napi_gro_receive+0x1f/0x2f
> [ 762.028222] [<ffffffff812769ff>] ? napi_skb_finish+0x1c/0x31
> [ 762.033941] [<ffffffffa024afcd>] ? igb_poll+0x6d9/0x9ee [igb]
> [ 762.039744] [<ffffffff8109034f>] ? handle_irq_event+0x40/0x55
> [ 762.045547] [<ffffffff8106fc3c>] ? arch_local_irq_save+0x14/0x1d
> [ 762.051609] [<ffffffff81276f55>] ? net_rx_action+0xa4/0x1b1
> [ 762.057239] [<ffffffff8104ad26>] ? __do_softirq+0xb8/0x176
> [ 762.062783] [<ffffffff81333cdc>] ? call_softirq+0x1c/0x30
> [ 762.068241] [<ffffffff8100aa57>] ? do_softirq+0x3f/0x84
> [ 762.073524] [<ffffffff8104af91>] ? irq_exit+0x3f/0x8f
> [ 762.078635] [<ffffffff8100a793>] ? do_IRQ+0x85/0x9e
> [ 762.083575] [<ffffffff8132cc53>] ? common_interrupt+0x13/0x13
> [ 762.089375] <EOI>
> [ 762.091469] [<ffffffff81061348>] ? enqueue_hrtimer+0x3f/0x53
> [ 762.097188] [<ffffffffa0430417>] ? arch_local_irq_enable+0x7/0x8
> [processor]
> [ 762.104288] [<ffffffffa0430dab>] ? acpi_idle_enter_c1+0x86/0xa2
> [processor]
> [ 762.111303] [<ffffffff8125d05d>] ? cpuidle_idle_call+0xf4/0x17e
> [ 762.117277] [<ffffffff81008298>] ? cpu_idle+0xa2/0xc4
> [ 762.122388] [<ffffffff8169db60>] ? start_kernel+0x3b9/0x3c4
> [ 762.128018] [<ffffffff8169d3c6>] ? x86_64_start_kernel+0x102/0x10f
> [ 762.134253] Code: 4d 02 3c 03 0f 86 59 02 00 00 0f b6 d0 44 39 ea 7f
> 32 83 c2 03 44 39 ea 0f 8f 45 02 00 00 48 85 db 74 18 48 8b 74 24 10 0f
> b6 c0 <8b> 96 d0 00 00 00 89 54 05 ff 41 80 4c 24 08 04 80 01 04 41 80
> [ 762.153593] RIP [<ffffffff8129fbe9>] ip_options_compile+0x1c1/0x435
> [ 762.159923] RSP <ffff88042f203af0>
> [ 762.163391] CR2: 00000000000000d0
> [ 762.167017] ---[ end trace e15d7b082f680b62 ]---
> --
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>

Good news! I cannot create any kernel panics with the following patches 
to 2.6.39-rc3 commit a6360dd37e1a144ed11e6548371bade559a1e4df while 
targeting either the host's bridged IP address or the guest virtual 
machine bridged IP addresses with the IP Stack Checker tools.

diff --git a/net/bridge/br_netfilter.c b/net/bridge/br_netfilter.c
index 008ff6c..cdb4423 100644
--- a/net/bridge/br_netfilter.c
+++ b/net/bridge/br_netfilter.c
@@ -221,6 +221,7 @@ static int br_parse_ip_options(struct sk_buff *skb)
         struct ip_options *opt;
         struct iphdr *iph;
         struct net_device *dev = skb->dev;
+       struct rtable *rt;
         u32 len;

         iph = ip_hdr(skb);
@@ -249,10 +250,18 @@ static int br_parse_ip_options(struct sk_buff *skb)
                 goto drop;
         }

-       /* Zero out the CB buffer if no options present */
-       if (iph->ihl == 5) {
-               memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
-               return 0;
+       memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
+       if (iph->ihl == 5)
+               return 0;
+
+       /* Associate bogus bridge route table */
+       if (!skb_dst(skb)) {
+               rt = bridge_parent_rtable(dev);
+               if (!rt) {
+                       kfree_skb(skb);
+                       return 0;
+               }
+               skb_dst_set_noref(skb,&rt->dst);
         }

         opt->optlen = iph->ihl*4 - sizeof(struct iphdr);
diff --git a/net/ipv4/inetpeer.c b/net/ipv4/inetpeer.c
index dd1b20e..9df4e63 100644
--- a/net/ipv4/inetpeer.c
+++ b/net/ipv4/inetpeer.c
@@ -354,7 +354,8 @@ static void inetpeer_free_rcu(struct rcu_head *head)
  }

  /* May be called with local BH enabled. */
-static void unlink_from_pool(struct inet_peer *p, struct inet_peer_base 
*base)
+static void unlink_from_pool(struct inet_peer *p, struct inet_peer_base 
*base,
+                            struct inet_peer __rcu **stack[PEER_MAXDEPTH])
  {
         int do_free;

@@ -368,7 +369,6 @@ static void unlink_from_pool(struct inet_peer *p, 
struct inet_peer_base *base)
          * We use refcnt=-1 to alert lockless readers this entry is 
deleted.
          */
         if (atomic_cmpxchg(&p->refcnt, 1, -1) == 1) {
-               struct inet_peer __rcu **stack[PEER_MAXDEPTH];
                 struct inet_peer __rcu ***stackptr, ***delp;
                 if (lookup(&p->daddr, stack, base) != p)
                         BUG();
@@ -422,7 +422,7 @@ static struct inet_peer_base *peer_to_base(struct 
inet_peer *p)
  }

  /* May be called with local BH enabled. */
-static int cleanup_once(unsigned long ttl)
+static int cleanup_once(unsigned long ttl, struct inet_peer __rcu 
**stack[PEER_MAXDEPTH])
  {
         struct inet_peer *p = NULL;

@@ -454,7 +454,7 @@ static int cleanup_once(unsigned long ttl)
                  * happen because of entry limits in route cache. */
                 return -1;

-       unlink_from_pool(p, peer_to_base(p));
+       unlink_from_pool(p, peer_to_base(p), stack);
         return 0;
  }

@@ -524,7 +524,7 @@ struct inet_peer *inet_getpeer(struct inetpeer_addr 
*daddr, int create)

         if (base->total >= inet_peer_threshold)
                 /* Remove one less-recently-used entry. */
-               cleanup_once(0);
+               cleanup_once(0, stack);

         return p;
  }
@@ -540,6 +540,7 @@ static void peer_check_expire(unsigned long dummy)
  {
         unsigned long now = jiffies;
         int ttl, total;
+       struct inet_peer __rcu **stack[PEER_MAXDEPTH];

         total = compute_total();
         if (total >= inet_peer_threshold)
@@ -548,7 +549,7 @@ static void peer_check_expire(unsigned long dummy)
                 ttl = inet_peer_maxttl
                                 - (inet_peer_maxttl - inet_peer_minttl) 
/ HZ *
                                         total / inet_peer_threshold * HZ;
-       while (!cleanup_once(ttl)) {
+       while (!cleanup_once(ttl, stack)) {
                 if (jiffies != now)
                         break;
         }