Subject: Broken "Make ip6_frags per namespace" patch

From: Alexey Dobriyan <[email-masked]>
Date: Thu, 17 Jan 2008 13:05:24 +0300

> commit c064c4811b3e87ff8202f5a966ff4eea0bc54575
> Author: Daniel Lezcano <[email-masked]>
> Date:   Thu Jan 10 02:56:03 2008 -0800
> 
>     [NETNS][IPV6]: Make ip6_frags per namespace.
>     
>     The ip6_frags is moved to the network namespace structure.  Because
>     there can be multiple instances of the network namespaces, and the
>     ip6_frags is no longer a global static variable, a helper function has
>     been added to facilitate the initialization of the variables.
>     
>     Until the ipv6 protocol is not per namespace, the variables are
>     accessed relatively from the initial network namespace.

> --- a/include/net/netns/ipv6.h
> +++ b/include/net/netns/ipv6.h

> @@ -11,6 +13,7 @@ struct netns_sysctl_ipv6 {
>  #ifdef CONFIG_SYSCTL
>  	struct ctl_table_header *table;
>  #endif
> +	struct inet_frags_ctl frags;

> --- a/net/ipv6/reassembly.c
> +++ b/net/ipv6/reassembly.c

> @@ -632,6 +625,11 @@ static struct inet6_protocol frag_protocol =
>  	.flags		=	INET6_PROTO_NOPOLICY,
>  };
>  
> +void ipv6_frag_sysctl_init(struct net *net)
> +{
> +	ip6_frags.ctl = &net->ipv6.sysctl.frags;
> +}

_This_ can't work. ip6frags is only one and ->ctl pointer is flipped
onto per-netns data. Changelog is also misleading: ip6_frags_ctl is
moved to netns not all ip6_frags.

Oopsing place below -- f->ctl dereference in preparation of mod_timer() call.

BUG: unable to handle kernel paging request at virtual address f5da8fc8
printing eip: c11d868a *pdpt = 0000000000003001 *pde = 0000000001728067 *pte = 0000000035da8000 
Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
Modules linked in: ebt_ip ebt_dnat ebt_arpreply ebt_arp ebt_among ebtable_nat ip6t_REJECT ip6table_filter ip6_tables ebtable_filter ebtable_broute ebt_802_3 ebtables des_generic nf_conntrack_netbios_ns nf_conntrack_ipv4 xt_state nf_conntrack xt_tcpudp ipt_REJECT iptable_filter ip_tables deflate zlib_deflate zlib_inflate cryptomgr crypto_hash cpufreq_stats cpufreq_ondemand cdrom cbc bridge llc blkcipher crypto_algapi arpt_mangle arptable_filter arp_tables x_tables ah6 af_packet ipv6

Pid: 0, comm: swapper Not tainted (2.6.24-rc7-net-2.6.25-nf-sysfs-n #30)
EIP: 0060:[<c11d868a>] EFLAGS: 00010246 CPU: 1
EIP is at inet_frag_secret_rebuild+0xaa/0xd0
EAX: f5da8fbc EBX: 00000000 ECX: c1310000 EDX: 00000100
ESI: f7cba000 EDI: f898f7a0 EBP: 00000040 ESP: c1310f90
 DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068
Process swapper (pid: 0, ti=c1310000 task=f7c9a580 task.ti=f7c9b000)
Stack: f898f7a8 f898f8a8 000ddcbd f898f7a0 f7cba000 c1310fc4 00000100 c1026d60 
       00000002 00000001 c1191183 c4779ddc c11d85e0 f898c860 f898c860 c12c4a88 
       00000001 c1308da0 0000000a c1023477 00000001 c130b640 c130b640 f7c9bf34 
Call Trace:
 [<c1026d60>] run_timer_softirq+0x120/0x190
 [<c1191183>] net_rx_action+0x53/0x220
 [<c11d85e0>] inet_frag_secret_rebuild+0x0/0xd0
 [<c1023477>] __do_softirq+0x87/0x100
 [<c10059cf>] do_softirq+0xaf/0x110
 [<c10233e3>] irq_exit+0x83/0x90
 [<c1010ce7>] smp_apic_timer_interrupt+0x57/0x90
 [<c10036e1>] apic_timer_interrupt+0x29/0x38
 [<c10036eb>] apic_timer_interrupt+0x33/0x38
 [<c1001460>] default_idle+0x0/0x60
 [<c10014a0>] default_idle+0x40/0x60
 [<c1000ea3>] cpu_idle+0x73/0xb0
=======================
Code: 8b 10 85 d2 89 13 74 03 89 5a 04 89 18 89 43 04 85 f6 89 f3 75 bb 45 83 fd 40 75 a5 8b 44 24 04 e8 4c 3f 01 00 8b 87 50 01 00 00 <8b> 50 0c 01 54 24 08 8d 87 38 01 00 00 8b 54 24 08 83 c4 0c 5b 
EIP: [<c11d868a>] inet_frag_secret_rebuild+0xaa/0xd0 SS:ESP 0068:c1310f90
Kernel panic - not syncing: Fatal exception in interrupt