Re: [Bugme-new] [Bug 11469] New: TUN with 1024 neighbours: ip6_dst_lookup_tail NULL crash

[Andrew Morton <akpm@linux-foundation.org>]

(switched to email.  Please respond via emailed reply-to-all, not via the
bugzilla web interface).

On Sun, 31 Aug 2008 09:44:36 -0700 (PDT) bugme-daemon@bugzilla.kernel.org wrote:

> http://bugzilla.kernel.org/show_bug.cgi?id=11469
> 
>            Summary: TUN with 1024 neighbours: ip6_dst_lookup_tail NULL crash
>            Product: Networking
>            Version: 2.5
>      KernelVersion: 2.6.26.3
>           Platform: All
>         OS/Version: Linux
>               Tree: Mainline
>             Status: NEW
>           Severity: normal
>           Priority: P1
>          Component: IPV6
>         AssignedTo: yoshfuji@linux-ipv6.org
>         ReportedBy: rdenis@simphalempin.com
> 
> 
> Latest working kernel version: none known
> Earliest failing kernel version: none tested
> Distribution: Debian
> Hardware Environment: Intel(R) Pentium(R) 4 CPU 2.80GHz, HyperThreaded
> Software Environment: SMT kernel, Debian glibc 2.7
> Problem Description:
> When an IFF_TUN (/dev/net/tun) device has more than 1023 IPv6 neighbors, a
> process context crash occurs. Backtrace follows:
> 
> BUG: unable to handle kernel NULL pointer dereference at 0000001d
> IP: [<f8b375bf>] :ipv6:ip6_dst_lookup_tail+0x95/0x15a
> *pde = 00000000
> Oops: 0000 [#14] SMP
> Modules linked in: ipx p8022 psnap llc p8023 i915 drm tun cpufreq_ondemand
> binfmt_misc fuse nf_conntrack_ftp nf_conntrack_ipv6 nf_conntrack_ipv4
> nf_conntrack ipv6 snd_intel8x0 snd_ac97_codec ac97_bus snd_pcm_oss
> snd_mixer_oss snd_pcm snd_seq_oss snd_seq_midi snd_rawmidi snd_seq_midi_event
> snd_seq snd_timer snd_seq_device snd intel_agp psmouse soundcore agpgart button
> processor snd_page_alloc parport_pc parport iTCO_wdt evdev pcspkr dm_mirror
> dm_log dm_snapshot dm_mod sg sr_mod cdrom e100 mii ehci_hcd uhci_hcd usbcore
> unix
> 
> Pid: 9950, comm: tunload Tainted: G      D   (2.6.26.3 #8)
> EIP: 0060:[<f8b375bf>] EFLAGS: 00210246 CPU: 0
> EIP is at ip6_dst_lookup_tail+0x95/0x15a [ipv6]
> EAX: 00000000 EBX: 00000000 ECX: ef4abdac EDX: 00000000
> ESI: ef4abd3c EDI: ef64ca00 EBP: ef4abcb8 ESP: ef4abc64
>  DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068
> Process tunload (pid: 9950, ti=ef4aa000 task=f7d45320 task.ti=ef4aa000)
> Stack: ef4abd58 ef4abdac f7cc0c00 ef4abc80 f8b36918 00000000 ef673e40 ef4abcc0
>        f8b381b2 00000002 f7cc0c00 ef7c3e00 f7cc0e24 00000000 ef4abca8 ef4abca8
>        c030bcfa ef4abcc0 00000000 ef4abed4 00000000 ef4abcc0 f8b377d5 ef4abdbc
> Call Trace:
>  [<f8b36918>] ? ip6_cork_release+0x2e/0x52 [ipv6]
>  [<f8b381b2>] ? ip6_push_pending_frames+0x1c9/0x3d9 [ipv6]
>  [<c030bcfa>] ? _spin_unlock_bh+0xd/0xf
>  [<f8b377d5>] ? ip6_dst_lookup+0xe/0x10 [ipv6]
>  [<f8b4c2b2>] ? rawv6_sendmsg+0x25d/0xc08 [ipv6]
>  [<c0151022>] ? filemap_fault+0x203/0x3d5
>  [<c02e8de0>] ? inet_sendmsg+0x2e/0x50
>  [<c02a24b8>] ? sock_sendmsg+0xcc/0xf0
>  [<c01365f5>] ? autoremove_wake_function+0x0/0x3a
>  [<c0136799>] ? remove_wait_queue+0x30/0x34
>  [<f8a08fbe>] ? tun_chr_aio_read+0x298/0x31f [tun]
>  [<c0211d67>] ? copy_from_user+0x2a/0x114
>  [<c02a2790>] ? sys_sendto+0xa5/0xc5
>  [<c02b3713>] ? neigh_periodic_timer+0x0/0x17a
>  [<c01365f5>] ? autoremove_wake_function+0x0/0x3a
>  [<c02a348f>] ? sys_socketcall+0x141/0x262
>  [<c0102f99>] ? sysenter_past_esp+0x6a/0x91
>  =======================
> Code: 22 83 fb 9b 74 37 8b 4d b0 8b 01 e8 35 96 77 c7 8b 45 b0 c7 00 00 00 00
> 00 89 d8 83 c4 48 5b 5e 5f 5d c3 8b 4d b0 8b 39 8b 47 2c <f6> 40 1d de 74 23 31
> db 89 d8 83 c4 48 5b 5e 5f 5d c3 64 a1 04
> EIP: [<f8b375bf>] ip6_dst_lookup_tail+0x95/0x15a [ipv6] SS:ESP 0068:ef4abc64
> ---[ end trace 1035c8e1d028e84b ]---
> 
> 
> Steps to reproduce:
> 
> Test case available at: http://www.remlab.net/files/divers/tunload.c
>