From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754242Ab0LAK23 (ORCPT ); Wed, 1 Dec 2010 05:28:29 -0500 Received: from mail-bw0-f46.google.com ([209.85.214.46]:58440 "EHLO mail-bw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751977Ab0LAK21 (ORCPT ); Wed, 1 Dec 2010 05:28:27 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=subject:from:to:cc:in-reply-to:references:content-type:date :message-id:mime-version:x-mailer:content-transfer-encoding; b=MiRKekUvWPCjLRJYGuhsD3988prEMhwxbgLEfSnjs9Iwjr7qJttkV9JAjGteHikquf qKhhTsjnYkXNWWzckxmUrND11IXSPVRFswuMdQ+wP4oCqbcM26XdfxuXZ7XnqvYYPqG3 I40oPpLuWWQPE4toopOGjjg4UKhvkUulQi9p8= Subject: Re: BUG in skb_dequeue (skb->next is NULL) (was: Re: Kernel crash with 2.6.36) From: Eric Dumazet To: Simon Schubert <2@0x2c.org> Cc: linux-kernel@vger.kernel.org, netdev In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Date: Wed, 01 Dec 2010 11:28:19 +0100 Message-ID: <1291199299.2856.499.camel@edumazet-laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Le mercredi 01 décembre 2010 à 09:02 +0000, Simon Schubert a écrit : > Frédéric L. W. Meunier <2 pervalidus.net> writes: CC netdev > > > Nov 7 16:21:23 pervalidus kernel: BUG: unable to handle kernel NULL pointer > dereference at (null) > > I can confirm the bug reported by Frederic. The culprit is at: > > next->prev = prev; > > in __skb_unlink(). > > Something must be putting NULL pointers in the skb list. > > Let me know how I can be of further help. > > > BUG: unable to handle kernel NULL pointer dereference at (null) > IP: [] skb_dequeue+0x59/0x90 > PGD 208379067 PUD 20a523067 PMD 0 > Oops: 0002 [#1] SMP > last sysfs file: /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq > CPU 1 > Modules linked in: binfmt_misc kvm_intel kvm ipt_MASQUERADE iptable_nat nf_nat > xfrm_user nf_conntrack_ipv4 xfrm4_tunnel tunnel4 nf_conntrack ipcomp xfrm_ipcomp > esp4 ah4 nf_defrag_ipv4 xt_TCPMSS xt_tcpmss xt_tcpudp iptable_mangle deflate > ip_tables zlib_deflate ctr x_tables twofish_generic twofish_x86_64 > twofish_common camellia serpent blowfish cast5 des_generic xcbc rmd160 > sha512_generic sha1_generic crypto_null af_key pppoe pppox xfs exportfs > snd_hda_codec_via snd_hda_intel snd_hda_codec snd_hwdep snd_pcm_oss > snd_mixer_oss snd_pcm snd_seq_dummy snd_seq_oss snd_seq_midi snd_rawmidi > snd_seq_midi_event snd_seq snd_timer ftdi_sio snd_seq_device usbserial hwmon_vid > coretemp snd lp tpm_tis ppdev tpm parport_pc asus_atk0110 tpm_bios parport > soundcore snd_page_alloc sha256_generic cryptd aes_x86_64 aes_generic dm_crypt > raid10 raid1 raid0 multipath linear raid456 async_pq async_xor xor async_memcpy > async_raid6_recov raid6_pq async_tx fbcon tileblit font bitblit softcursor usb > > Pid: 2229, comm: pulseaudio Not tainted 2.6.36 #10 P5Q-VM DO/System Product Name > RIP: 0010:[] [] skb_dequeue+0x59/0x90 > RSP: 0018:ffff880221927a78 EFLAGS: 00010097 > RAX: 0000000000000282 RBX: ffff88017a6d5e14 RCX: ffff88022236d200 > RDX: 0000000000000000 RSI: 0000000000000282 RDI: ffff88017a6d5e14 > RBP: ffff880221927a98 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000293 R12: ffff88022236d200 > R13: ffff88017a6d5e00 R14: 0000000000000000 R15: 0000000000000000 > FS: 00007fedd4d9f740(0000) GS:ffff880001e80000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b > CR2: 0000000000000000 CR3: 000000020837a000 CR4: 00000000000006e0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 > Process pulseaudio (pid: 2229, threadinfo ffff880221926000, task > ffff8802210096d0) > Stack: > ffff88022236d200 ffff88022236d228 ffff88022236d200 ffff880221927f18 > <0> ffff880221927be8 ffffffff814ef0fa ffff880221927e4c ffff880221927eb4 > <0> 0000000000000040 ffff8802210096d0 ffff8802210096d0 ffff88017a6d5ea4 > Call Trace: > [] unix_stream_recvmsg+0x1aa/0x790 > [] sock_recvmsg+0xfd/0x130 > [] ? pollwake+0x0/0x60 > [] __sys_recvmsg+0x144/0x2e0 > [] ? pollwake+0x0/0x60 > [] ? finish_task_switch+0x4a/0xd0 > [] ? schedule+0x411/0xa50 > [] sys_recvmsg+0x49/0x80 > [] system_call_fastpath+0x16/0x1b > Code: e5 74 4f 4d 85 e4 74 26 41 83 6d 10 01 49 8b 0c 24 49 8b 54 24 08 49 c7 04 > 24 00 00 00 00 49 c7 44 24 08 00 00 00 00 48 89 51 08 <48> 89 0a 48 89 c6 48 89 > df e8 39 93 0f 00 4c 89 e0 48 8b 5d e8 > RIP [] skb_dequeue+0x59/0x90 > RSP > CR2: 0000000000000000 > ---[ end trace d4be3de9fdd70935 ]--- > > cheers > simon > > Is it reproductible ? On previous kernel (say 2.6.35) you never hit this bug ?